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Brewing Water

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Title: Brewing Water


1
Brewing Water
  • 6 October 2008
  • A.J. deLange
  • Burp Education Series
  • Based on class given 28 April 1996

2
Perspective
  • The community (and I) have learned a few things
    about brewing water since 1996 (when I last gave
    this class)
  • Then Slavish attention to reproducing brewing
    cities ion profiles
  • A lot of people did a lot of hard work based on
    bogus data (published ion profiles)
  • Now Emphasis on getting proper mash pH with
    brewing liquor that more or less matches
    traditional profile
  • Recognition of Residual Alkalinity as a powerful
    tool for evaluating and comparing brewing water
    samples
  • Tweaking stylistic ions to taste (and
    authenticity).
  • Why put it in if you are just going to take it
    out (e.g. Munich Helles)?
  • Often no information whatsoever on type of water
    required for a particular style - this is
    starting to change
  • Most modern water supplies are generally good for
    brewing most beers.
  • Big Exception Chloramine!!

Note Red font denotes key concepts - take
special note of these
3
Approach
  • Water chemistry is intricate and detailed if not
    complex
  • In a couple of hours I can only skim the surface
  • There wont be time to thoroughly explain many of
    the concepts
  • Go back and look at the slides again at leisure
  • Some slides are in here with that intention - we
    wont do much more than mention them
  • For practical knowledge you must explore further
    on your own
  • Papers on CD
  • Most of the bloody details are found in the
    Cerevesia paper
  • Spreadsheet on CD
  • This will be your best friend in terms of
    practical applications.
  • Books (see list at end)
  • Internet

4
There are Two Aspects to Brewing Water
  • I Water chemistry has great influence on mash pH
    thus great influence on nature of the beer
  • Full understanding of this requires knowledge of
    acid-base equilibrium chemistry, intricate
    calculations
  • Reviewed in Cerevesia article (on handout CD)
  • Fortunately, a simple (to use) Excel spreadsheet
    (on handout CD) can handle all of this for you
  • You need to know how to use it and what the
    numbers mean - not how to program it
  • II Certain ions influence flavors - just as they
    do in any other form of cooking.
  • Salt to taste

5
Your Goals
  • Understand
  • Relationship between beer and water its made
    from
  • Fundamentals of chemistry related to brewing
    water
  • Atoms, molecules, ions, moles, equivalents,
    acids, titration
  • pH, Alkalinity, Residual Alkalinity (RA) and
    Hardness
  • These are the key concepts
  • Be able to
  • Read a water report
  • Check it for validity (using spreadsheet)
  • Treat water to
  • Remove chlorine and chloramine
  • Reduce bicarbonate (alkalinity) and iron (if you
    have it)
  • Control the pH of your mash
  • Establish an approximation to a desired ion
    profile

6
Quotations
  • Wine is made by farmers. Beer is made by
    engineers. (?)
  • A distinction is frequently drawn in the
    industry between the theoretical man who tries to
    explain everything from a scientific point of
    view, and the practical man who relies on
    empirical knowledge and experience. A good brewer
    should be able to steer a middle course between
    these two extremes - Jean deClerck
  • The third group, the smallest, are the
    Noonanians, the triple decoction cultists.
    Eighteen hour brew days, elaborate water
    modifications you wonder how they stay married.
    - Delano DuGarm

7
Quotations II
  • Water contains three ions which influence the pH
    of wort bicarbonate, calcium and magnesium. The
    bicarbonate ion has a pH raising effect, the
    other two lower it. The pH lowering effect of
    magnesium ions is only half that of calcium ions.
    Depending on the ratio of the waters content of
    bicarbonate on the one hand and calcium and
    magnesium on the other, the pH raising effects of
    the bicarbonate is more or less compensated or
    balanced. Thus experiment has shown that to
    balance 1 equivalent of bicarbonate ion 3.5
    equivalents of calcium or 7 equivalents of
    magnesium ion are required. With respect to the
    pH raising property of the total alkalinity of
    the brew water, thus, a definite part is
    balanced. The remainder, the residual alkalinity,
    can serve as a measure of the pH raising effect
    of the water.
  • Paul Kohlbach, Die Einfluss des Brauwassers auf
    das pH von Würze und Bier, Monatsschrift für
    Brauerei, Berlin, Mai 1953
  • Whole paper is on CD. Read it!

8
Topics
  • Part 0 Beer and Water
  • Part 1 Fundamentals of Chemistry
  • Part 2 Carbon Dioxide, Water, Limestone, pH,
    Hardness, Alkalinity
  • Part 3 Adding Malt Phosphate to the Picture ,
    Residual Alkalinity
  • Part 4 Water reports
  • Part 5 Water testing
  • Part 6 Water Treatment
  • Part 7 Synthesis of water with a given ion
    profile
  • Part 8 Comparison Beer

9
Handout CD Contains
  • A copy of this presentation
  • Translation of Paul Kohlbachs seminal paper
    (1953)
  • A set of slides from a lecture given at DeClerck
    Chair XI (Louvaine-la-Neuve, Sept 2004)
  • Copy of the paper (based on that lecture) from
    Cerevesia 29(4) 2004
  • Microsoft Excel spreadsheet which implements the
    significant brewing water chemistry calculations
  • Two part BT article on Alkalinity (unpublished)
  • BT article on Chloramine
  • New York Times Science article (geology and
    beer).
  • 54 recipes for water of various brewing cities
    from common salts and distilled water.

10
Part 0Overview - Beer and Water
11
Water and Beer Style
  • Water is heavy (1 kg/L 8.3 Lbs/gal.)
  • Barley, malt and hops can be cost effectively
    moved fairly long distances - water can not.
  • Therefore, absent ability to treat it, local
    water determined what local beer was like
  • Soft water Bohemian Pils
  • Hard, bicarbonate Water Munich Dunkles, London
    Ales
  • Remove bicarbonate and you can make Helles
  • Hard Sulfate Water Burton Ales

12
The First of the Two Aspects
  • Bicarbonate is a base - its alkaline
  • It raises mash pH malt enzymes become less
    effective
  • It must be neutralized or removed (so pH is kept
    low)
  • Hardness (Ca, Mg) plus malt phosphate
    neutralize it
  • Alkalinity (water bicarbonate) not neutralized by
    water hardness malt phosphate is called
    Residual Alkalinty
  • Acid neutralizes it
  • Sulfuric, hydrochloric, lactic, acid in dark malt
  • High alkalinity water requires lots of hardness,
    acid and or dark malt to neutralize it (and
    conversely)
  • Theme Contest between alkalinity (bad) and
    hardness (good) for control of mash pH.

13
Hardness Alkalinity for Several Cities
Bad
OK
Good
OK
RA Alkalinity - (Ca_hardness
Mg_hardness/2)/3.5
14
Part 1 Fundamentals of ChemistryAtoms,
Molecules, Ions, Acids, Bases
15
For Further Information
  • We can only skim (rapidly) the surface at the
    highest level today
  • Nothing here beyond college freshman chemistry
  • Should today stimulate your interest, review
    freshman chemistry or biochemistry text
  • Pay particular attention to ionic equilibrium
    (law of mass action), acid/base chemistry,
    Henderson Hasselbalch equation.
  • Read Cerevesia article on CD

16
Atoms
  • Smallest particle of elemental matter with
    nucleus of positively charged protons and
    uncharged neutrons
  • of mass 1.673E-24 grams (protons and neutrons
    slightly different)
  • Surrounded by negatively charged electrons
  • With mass 0.000911E-24 grams (1/1822 of proton)
  • Number of electrons equals number of protons
  • Atom has a net charge of 0.
  • Electrons group into shells
  • Most of the elements well deal with like to have
    8 electrons in outer shell
  • The number of protons (and electrons) determine
    which element the atom is
  • 1 H, 2 He, 3 Li, 4 Be, 5 B, 6 C 7 N,
    8 O 9 F, 10 Ne
  • Number of neutrons determines which isotope
  • 6 protons 6 neutrons 12C (normal) 6p
    8n 14C (radioactive)

17
Chemical Symbols
  • Each element (atom type) is represented by a
    symbol
  • Its often pretty obvious which element is meant
  • H Hydrogen C Carbon O Oxygen Ca
    Calcium Mg Magnesium S Sulfur
  • But not always
  • Na Sodium (L. Natrium) K Potassium (L.
    Kalium) Fe Iron (L. Ferrum) Hg Mercury
    (L. Hydrargyrum)
  • Combined atom symbols represent compounds
  • NaCl Sodium chloride HCl Hydrochloric Acid
    CaCl2 Calcium chloride H2CO3 Carbonic
    acid CaCO3 Calcium Carbonate CaSO4.2H2O
    Calcium Sulfate with 2 waters of hydration.
  • Subscript indicates number of atoms in molecule
  • 1 Molecule of CaCO3 has 1 calcium, 1 Carbon, 3
    Oxygen atoms
  • Ion (electrically charged atom or molecule) is
    indicated by element or compound symbols with
    charge shown
  • Na Sodium ion Ca Calcium ion HCO3-
    Bicarbonate

18
IONS
  • Noble gasses Helium, Neon, Argon have complete
    electron shells chemically stable
  • Atoms may take on or release electrons to
    complete or leave a complete shell
  • Sodium (Ne1e-) Na --gt e- Na Sodium Ion
  • Noble gas represents the electronic structure
    of that gas
  • Giving up 1 electron leaves Neon (10 e-) shell
    structure
  • Could give it to e.g. chlorine
  • Chlorine (Ne7e-) Cl e- --gt Cl- Ion
  • (Ne8e- Ar)
  • Calcium (Ar2e-) Ca --gt 2e- Ca Ion
  • Take away 2 electrons leaves Argon shell
    structure
  • Hydrogen (1 e-) H --gt e- H Hydrogen Ion
  • Naked proton (quickly attaches to a water
    molecule)

19
Molecules
  • Atoms can also share (or give) electrons with
    (to) other atoms in order to complete shells
  • Carbon (C) has 4 electrons in its outer shell
    He4e-
  • Hydrogen (H) has 1 electron 1e-
  • If carbon shares the electrons from each of 4
    hydrogen atoms it completes its outer (valence)
    shell
  • He 4e- 4e-(shared from hydrogens) Ne
  • Each hydrogen shares one of carbons electrons
  • 1e- 1e- (shared from carbon) He
  • CH4 is the gas methane
  • Na gives e- to Cl. Na attracts Cl- --gt NaCl
  • Atoms so combined are called molecules the
    constituents of compounds.

20
Dissociation
  • Some molecules (acids) may release or take on
    (bases) protons (hydrogen ions) thus becoming
    ions themselves
  • Carbonic Acid H2CO3 --gt H HCO3-
    Bicarbonate ion
  • Ammonia (base) NH3 H --gt NH4 Ammonium
    ion
  • Sulfuric Acid H2SO4 --gt H HSO4-
    Bisulfate ion
  • Hydrochloric Acid HCl --gt H Cl-
    Chloride ion
  • Ions can do this too and become doubly ionized or
    un-ionized
  • Bicarbonate ion HCO3- --gt H CO3--
    Carbonate ion
  • Bicarbonate ion HCO3- H --gt H2CO3
    Carbonic acid
  • Molecules (or ions) which give up protons are
    acids in the Lowry-Brønstead sense (there are
    other definitions)
  • Molecules (or ions) which take up protons are
    bases in the Lowry-Brønstead sense.

21
Chemical Equations
  • Reactants on left, products on right
  • Equation in the sense that numbers of atoms (of
    each type) and charges must be equal on each side
  • Ca(OH)2 Ca 2HCO3- --gt 2CaCO3 2H2O
  • This says that 1 molecule of calcium hydroxide
    (slaked lime) reacts with 1 calcium ion and 2
    bicarbonate ions producing 2 molecules of calcium
    carbonate (chalk) which precipitates (underbar)
    and 2 molecules of water
  • 2 Calcium, 2 Carbon, 8 Oxygen, 4 Hydrogen, 0
    charge on each side
  • --gt indicates that reaction proceeds from left to
    right but not in other direction (many, indeed
    all, reactions proceed in both directions if
    conditions are right but one is sometimes
    preferred.)
  • This reaction is commonly used by brewers to
    remove bicarbonate from alkaline water.
  • Because it removes calcium, a component of
    hardness, as well it is usually thought of as a
    water softening treatment.

22
Measurement of Chemicals
  • RE last slide each molecule of lime will remove
    2 bicarbonate ions. How much lime do we need to
    buy to process x gallons of water?
  • Clearly we need to have some idea of what a
    molecule weighs and how many we need.
  • Molecules, like atoms and ions, are made up of
    protons and neutrons which contribute nearly all
    the weight as electron weight is negligible
  • One proton weighs 1 Dalton (1 Atomic Mass Unit)
  • How many protons weigh one gram?
  • Answer 6.023E23 called Avogadros Number.
  • Avogadros number of Daltons 1 gram
  • Avogadros number of anything (atoms, molecules,
    ions, electrons, rutabagas, even furry blind
    subterranean mammals) is called one mole

23
Gram Molecular Weights Weight of 1 mole
  • Hydrogen 1 proton. 1 mole should weigh about 1
    gram. Actual GMW 1.00794
  • Oxygen 8 protons, 8 neutrons. 1 mole should
    weigh about 16 grams. Actual value 15.9994
  • Calcium 20 protons, 20 neutrons. 1 mole should
    weigh about 40 grams. Actual value 40.078
  • Ca(OH)2 38 protons, 38 neutrons. 1 mole should
    weigh about 74 grams. Actual GMW 74.093
  • HCO3- 31 protons, 30 neutrons. 1 mole should
    weigh about 61 grams. Actual GMW 61.03
  • Thus 1 molecule of Ca(OH)2 reacting with 2 HCO3-
    ions implies that 6.023E23 (1 mole 74.093grams)
    of Ca(OH)2 will react with 12.046E23 (2 moles
    122.06 grams) of HCO3- and so on in that
    proportion
  • Example To decarbonate water with 61 milligrams
    (mg) of bicarbonate (1 millimole) per liter would
    require 1/2 mMol of Ca(OH)2 weighing 74.093/2
    37.046 mg per liter.

24
Equivalent Weight
  • Sometimes specified weights are based on moles of
    charge rather than moles of ions or atoms
  • Singly charged HCO3- 31 protons, 30 neutrons.
    GMW 61.03 means 61.03 grams has a charge of 1
    mole of (-) charges. Equivalent weight 61.03.
  • Doubly charged Ca 20 protons, 20 neutrons. GMW
    40.078 means 40.078 grams carries 2 moles of ()
    charge. 20.039 grams carries 1 mole. Equivalent
    weight 20.039
  • Equivalent weight gram molecular weight divided
    by charge.
  • Alkalinity (HCO3-) and hardness (Ca, Mg) are
    often expressed in milliequivalents per liter
    (mEq/L sometimes called mVal/L or just mVal).
  • Sometimes given as 50 times mEq/L - called parts
    per million as CaCO3
  • This is seen a lot. Note 1 ppm 1 mg/L (as
    water weighs 1 kg/L)

100mg 1mMol
44mg 1mMol
18mg 1mMol
122mg 2mMol
40mg 1mMol
CaCO3 CO2 H20 --gt 2HCO3- Ca
2mEq 100ppm as CaCO3
2mEq 100ppm as CaCO3
25
Example of Calculation
  • Being an environmentally conscientious brewer you
    wish to neutralize your standard lye cleaning
    solution (1 pound lye in 5 gal water) before
    dumping it down the drain. How much acid is
    needed?
  • Na(OH) H2O --gt Na (OH)- H2O
  • Lye GMW 40 1 lb 454 g 454/40 11.36 Mol
    11.36 Eq (OH)-
  • H (OH)- --gt H2O Need 11.36 Eq H
  • Sulfuric Acid MW 98 H2SO4 --gt 2H SO4--
  • 11.36/2 Mol H2SO4 yields 11.36 Eq H
  • 9811.36/2 556 grams 1.23 lbs concentrated
    sulfuric acid required.
  • 11.36 Mol of Na 11.36/2 Mol SO4-- (11.36/2
    Mol Na2SO4, MW 142 11.36142/2 0.806 kg) go
    down drain (wrong on CD)
  • Hydrochloric Acid MW 36.46 HCl --gt H Cl-
  • 38 HCl solution (23 Baume) is 12.29 Normal
    meaning it contains 12.29 Eq H per litre.
    Therefore need 11.36/12.29 0.917 L of 38 HCl
  • 664 g NaCl (table salt) goes down drain
  • Add acid to solution until pH neutral rather than
    relying on calculation

26
Another Example Calculation
  • Water tests 3 mg/L available chlorine (from
    chloramine). How much potassium metabisulfite
    (K2S2O5 MW 222.32) is required to treat 20 gal
    (76 L)
  • 2K S2O5-- 2H2NCl 3H2O --gt 2K 2SO4--
    2H 2Cl- 2NH4
  • Each mole of chlorine requires 0.5 mole of
    bisulfite ion and produces 1 mole of sulfate, 1
    equivalent of hydrogen ions, 1 mole of chloride
    ions and 1 mole of ammonium ions.
  • 3 mg/L Cl 3/35.45 0.0846 mMol/L requiring
    0.0423 mMol/L metabisulfite and producing 0.0846
    mMol/L sulfate, hydrogen, chloride and ammonium
    ions.
  • The GMW of potassium metabisulfite is 222.32
    mg/mMol so we need 9.4 mg/L or 714 mg total (one
    lot of Campden tablest we measured weighed 695
    mg)
  • The hydrogen ions, 0.0846 mEq/L represent a
    reduction in alkalinity of 50 times this or 4.2
    ppm as CaCO3.
  • As each bound chlorine atom is converted to a
    chloride ion the chloride level will increase by
    3 mg/L
  • 0.0846 mMol/L 96 mg/mMol 8.12 mg/L increase
    in sulfate (Pils brewers take note)
  • 0.0846 mMol/L18 mg/mMol 1.5 mg/L increase in
    ammonium ion (your yeast will love it)

27
Part 2Carbon Dioxide, Water Limestone
Hardness Alkalinity
28
Carbon Dioxide CO2 MW 44.01
  • Spewed by volcanoes
  • Taken up by plants -gt sugar, starch oxygen
  • 6CO2 6H2O ------gt C6H12O6 6O2
  • Released by carbohydrate oxidation (including
    respiration, fermentation, decay)
  • CnH2nOn nO2 --gt nCO2 nH2O
  • A greenhouse gas
  • Though not a very effective one (10 re water
    vapor)
  • Present in the atmosphere to the extent of 0.03
    (0.0003Atm 0.3 hPa)
  • Absorbed/released by oceans, rivers, lakes
  • Sequestered by animals which build shells from it
  • Dissolves in water to form carbonic acid which,
    in turn, dissolves limestone
  • This is the property of significance to brewers
    (and spelunkers).

light
29
Water
  • Continuous cycle of evaporation, condensation,
    precipitation
  • Ultimately comes to us from rain, snow, meltoff..
  • Runs over surface of earth into a stream/pond
  • In equilibrium with atmospheric CO2
  • Leaches substances from surface organic/inorganic
    materials with which it comes in contact
  • Or percolates into ground and is withdrawn from
    well penetrating aquifer
  • In equilibrium with subterranean CO2 (respiring
    bacteria)
  • Typically more acidic (dissolved CO2)
  • Dissolves minerals from rock with which it comes
    in contact
  • Limestone caves
  • Typically more mineral content than surface water
  • Usually clearer, fewer bacteria than surface
    (well filtered)
  • May be in the ground for years.

30
Carbonic Acid MW 62.03
  • CO2 dissolves in water to form carbonic acid
  • CO2 H2O lt--gt H2CO3
  • indicates this is both dissolved but not
    hydrated CO2 and hydrated CO2
  • Arrow is two headed. Carbonic acid can decompose
    into water and CO2
  • which can give up a proton to form bicarbonate
    ion
  • H2CO3 lt--gt H HCO3-
  • Ability to give up proton defines H2CO3 as an
    acid
  • In reverse, HCO3- can take up a proton to form
    H2CO3. This defines a base
  • which can give up its proton to form carbonate
  • HCO3- lt--gt H CO3--
  • The fact that it does so defines bicarbonate as
    an acid.
  • Thus bicarbonate is an acid and a base (it is
    amphoteric)
  • Which it behaves as depends on pH (at brewing pH
    it is basic)
  • In reverse, CO3-- takes up a proton to form
    HCO3- . CO3-- is a base
  • which can coalesce with calcium ion to
    precipitate chalk
  • CO3-- Ca lt--gt CaCO3 (only slightly soluble)

31
Calcium Carbonate MW 100.087
  • Ca CO3-- --gt CaCO3 (lime, chalk, limestone)
  • Happens in the bodies of marine animals
  • Main source of limestone - sequesters CO2, sends
    to bottom
  • 10 of all sedimentary rock
  • Happens when hard bicarbonate water is heated
  • Popular method for decarbonating brewing water
  • Or when hard bicarbonate water evaporates
  • Shower heads
  • Stalactites/Stalagmites
  • Dissolved by carbonic acid - source of calcium
    hardness
  • CaCO3 H2O CO2 --gt CaCO3 H2CO3 --gt 2HCO3-
    Ca
  • Surface and ground water are hard alkaline
  • Cave formation underground paCO2 much higher
    (hence more carbonic) because of respiring
    bacteria

32
Law of Mass Action
  • In any reaction mA nB lt--gt kC jD
  • CkDj/AmBn K, a constant (constant
    temp.)
  • A activity of A
  • For a gas A is approximately the partial
    pressure
  • For a dissolved substance A is approximately
    the concentration (moles per liter)
  • For a solid A 1
  • Define pA - log10A
  • Then kpC jpD - mpA - npB pK
  • If A B lt--gt C (underscore precipitation)
    then
  • AB lt Ks (solubility product) No
    precipitation occurs
  • AB gt Ks supersaturated. Precipitation
    usually occurs
  • AB Ks saturated. No precipitation
  • pA pB pKs at saturation

33
Carbonic - Loss of 1st Proton
  • H2CO3 lt--gt H HCO3-
  • HHCO3-/H2CO3 K1
  • pH pHCO3- - pH2CO3 pK1
  • Henderson-Hasselbalch Equation
  • px - log x
  • pH pH is special - more to follow on this
  • pH - pK1 pH2CO3- pHCO3-
  • rearranged
  • 10 pH - pK1 10pH2CO3 - pHCO3-
    HCO3- / H2CO3 r1 ratio
    bicarbonate to carbonic
  • Took antilog of both sides
  • Note if pH pK1 then r1 1 HCO3- H2CO3

34
Carbonic - Loss of 2nd Proton
  • HCO3- lt--gt H CO3--
  • HCO3--/HCO3- K2
  • pH pCO3-- - pHCO3- pK2
  • pH - pK2 pHCO3-- pCO3--
  • 10 pH - pK2 10pHCO3- - pCO3-- CO3-- /
    HCO3- r2 ratio carbonate to bicarbonate
  • If pH pK2 then r2 1 CO3-- HCO3-
  • Solutions tend to resist pH changes near their
    pKs
  • This is called buffering

35
H2CO3, HCO3-, CO3-- Fractions
  • If there are x moles of carbonic, there are r1x
    moles of bicarbonate and xr1r2 moles of carbonate
    for a total of CT x(1 r1 r1r2) xd
  • CT total carbo
  • The fraction which is carbonic is x/xd 1/d f1
  • The fraction which is bicarbonate is r1 times
    this r1/d f2
  • The fraction which is carbonate is r2 times this
    or r1r2d f3

36
Distribution of carbo species
pHs
pK2 10.35
pK1 6.38
Alkalinity is defined as the number of mEq of
acid required to change the pH of a sample from
its pH at the source (pHs) to pH 4.3
37
Alkalinity
  • Definition the number of mEq of acid required to
    change pH of a sample to a reference pH (usually
    pHr 4.3)
  • Sum of
  • Acid required to change carbonate to carbonic
  • Acid required to change bicarbonate to carbonic
  • Acid required to increase H to (1000)10-pHr
    mEq/L
  • Acid require to neutralize (OH)-
  • r reference pH, s sample pH, pKw 14
  • Units mEq/L (thats why the factor of 1000 is
    there)
  • CT total mmol/K carbonic, bicarbonate,
    carbonate
  • Equation can be solved for CT if alk, pHr and pHs
    are known
  • Thus choice of pHr is somewhat arbitrary

alk CT(f1,r - f1,s f3,s- f3,r)
(1000)10(pHs-pHr) (1000)10(pKw-pHr-pHs)
38
Solubility Product
  • CaCO3--lt Ks Solubility Product
  • If CaCO3-- Ks water is called saturated
  • pCapCO3--lt pKs
  • Calcium carbonate is not very soluble in water
  • To precipitate carbo (and hardness) establish
    conditions which violate inequality
  • Increase pH thus f3 (Drive off CO2 by heat,
    sparge)
  • Decrease Ks (raise temperature)
  • Increase Ca (add gypsum or CaCl2)
  • Combinations (Ca(OH)2 increases pH and Ca)

39
Combine Equations
  • Add Eqns for dissolving CO2, CaCO3 saturation,
    water dissociation and electric neutrality
  • CO2 Dissolves
  • A proton is lost
  • A 2nd proton is lost
  • CaCO3 Saturation
  • Water dissociates
  • The total charge is 0
  • Define
  • Substitute into charge neutrality equation,
  • Solve (root finder) for pH which satisfies this
    equation
  • Substitute back

pfm accounts for fact that solutions are not
ideally dilute. We will ignore this.
40
Why All this Horrible Math?
  • It is what allows us to
  • Validate a water analysis
  • Calculate alkalinity and estimate the acid
    required for proper mash pH
  • Synthesize any water ion profile from any
    starting water (e.g. salt additions to get Burton
    water from my well water)
  • Determine whether water is stable (saturated with
    respect to CO2 or CaCO3
  • Make charts like one on next slide
  • It is what is behind the spreadsheet on the CD

41
CO2 Over Water in Equilibrium with CaCO3
42
Review - Dissolving Limestone
Alkalinity comes from limestone and the carbonic
acid which Is required to dissolve it.
Calcium hardness comes from dissolved limestone.
43
pH
  • Søren Peter Lauritz Sørenson (1868 -1939)
  • Worked at Carlsberg Laboratory
  • Studied amino acids, proteins enzymes
  • Their behaviour (total electric charge) depends
    on hydrogen ion concentration (mechanism weve
    been discussing).
  • Sought convenient scale for specifying H
    (1909)
  • Called it pondus (L. a weight) hydrogenii i.e. pH
    -log10H
  • For pure water H 10-7 Mol/L thus pH 7
  • For .001 N acid H 10-3 Mol/L thus pH 3
  • pH lt 7 Acid, sour, beer, wine, soda
    (phosphates), vinegar, lemon, lime (citrus),
    sauerkraut, sour cream, kimche
  • pH 7 Neutral, water, blood, brine
  • pH gt 7 Base, bitter, lye, lime (slaked), soda
    ash

44
Importance of pH in Brewing
  • Necessary to calculate carbo species distribution
    in water
  • As pH changes charge distribution on proteins it
    changes conformation of enzymes
  • Brewing water treatment is done to get enzymes
    properly conformed for protein lysis, starch to
    sugar conversion
  • Happens in range pH 5.2-5.7
  • Proper charge distribution on proteins (chains of
    amino acids) in boil (iso-electric point net
    charge 0) enhances coagulation

Charge (Q) shown for simplest amino acid, Glycine
(R H)
Note For some amino acids (Arginine, Lysine,
Tyrosine.) R may be ionizeable in which case
other charge values are possible
45
Importance of pH II
  • Tanins not extracted from barley husks if sparge
    pH lt 6
  • Yeast produce acid to kill competing organisms
  • Thus pH drop is first sign of healthy
    fermentation
  • pH has an effect on stability of colloids in
    finished beer.
  • pH modulates formation of melanoidins
  • IOW, each part of the brewing process proceeds
    best in a range of pH (and temperature)
  • XI DeClerck Chair 3 Days of lectures on pH
    Paradox devoted to this subject
  • Advanced brewer feels as helpless without his pH
    meter as he does without his thermometer.

46
pH Measurement
  • Originally with dye which changes color at
    particular pH
  • Litmus Test from a lichen (red lt 7, blue gt7)
  • Phenolpthalein, bromcresol red, methyl orange
    (4.3)
  • Electronically potential developed across
    specially prepared (delicate) glass bulb
    dependent on pH difference between inside and out
  • Potential measured between electrode inside bulb
    and reference junction electrically connected to
    solution being measured (outside bulb)
  • Very feeble current. Extremely high impedance
    amplifier required
  • 57 millivolt change per unit pH change
  • Depends on temperature - temperature compensation
    essential
  • Note pH also changes with temperature (because
    pKs do). This is a separate effect
  • Special field effect transistors (ISFET)
  • Much more durable, store dry
  • Modern meters more dependable, last longer, less
    expensive, feature rich (ATC, auto buffer
    recognition) but still not for the casual user.
  • Must be calibrated frequently with buffers of
    known pH

47
Part IIIAdding Phosphate, Residual Alkalinity
48
Phosphoric Acid Chemistry
  • Same as carbonic except
  • The oxide is a solid P2O5 3H2O --gt 2H3PO4
  • Compare CO2 H2O --gt H2CO3
  • General reaction for oxoacids
  • Includes carbonic, phosphoric, nitric, sulfuric
  • Three protons
  • H3PO4 --gt H H2PO4- --gt 2H HPO4-- --gt 3H
    PO4---
  • Three (not the same as carbonic) pKs (2.12,
    7.21, 12.67), three rs, three fs.
  • Calcium phosphate is very insoluble
  • The smallest amount of phosphate will pull out
    lots of calcium
  • This is why trisodium phosphate was used as water
    softener
  • 3Ca 2Na3PO4 ---gt Ca3(PO4)2 6Na
  • And why malt phosphate lowers pH of hard water
  • Net reaction releases protons (hydrogen ions) -
    later slide

49
Phytic Acid from Malt
50
Malt Phosphate
  • Up to 2 of malt weight is phosphate
  • In the form of phytin, salt of myoinositol
    hexaphosphate
  • Enzyme phytase breaks down phytin releasing
    inorganic phosphate (H2PO4-, HPO4--) and B
    vitamin myoinositol (good for yeast)
  • Phytase survives only mild kilning i.e. active in
    pale base malts only
  • Phosphate coalesces with any calcium in water,
    precipitates and releases protons which lower
    mash pH.
  • Paul Kohlbach observed that 3.5 mEq of Ca or 7
    mEq Mg neutralize 1 mEq alkalinity
  • Neutralize here means that the pH of a mash with
    all alkalinity neutralized has same pH as a
    distilled water mash ( 5.7)
  • Defined Residual Alkalinity RA alk. -(Ca
    Mg/2)/3.5
  • Alkalinity, hardnesses and residual alkalinity
    all in units of either mEq/L or ppm as CaCO3.
  • Also noted 0.085 pH shift for each mEq/L (50 ppm)
    of RA

51
Residual Alkalinity Chart
  • Residual Alkalinity RA alk. -(Ca
    Mg/2)/3.5
  • Define Hard_eff -(Ca Mg/2)
  • Effective hardness equals calcium hardness plus
    half magnesium hardness
  • Then RA alk. - Hard_eff/3.5
  • Solve for alk alk RA Hard_eff/3.5
  • Plotting alk vs. Hard_eff for a given RA gives a
    straight line which crosses the alk axis at RA
    and has slope 1/3.5
  • This is the chart from earlier in the
    presentation
  • RA values in increments of 50 ppm as CaCO3
    corresponding to pH shift increments of 0.085
  • Above heavy line (RA 0) pH will be higher than
    distilled water mash, below it, pH will be higher
  • RA lt 50 generally OK (dotted line)

52
RA Chart
53
Use of Chart - Example
  • Edinburg (Edn2) Alk 180, Hard_eff 340, RA 85, pH
    5.89 is too high
  • Reduce alkalinity by 180 - 100 80 to get to RA
    0 and pH 5.75
  • Add 80/50 1.6 mEq/L acid (e.g. HCl, H2SO4)
  • Decarbonate water. Can get to approximately 50
    ppm as CaCO3, RA 35, pH 5.69
  • Could also get to this RA by adding (180 -50)/50
    2.6 mEq/L acid
  • Add (620 - 340)/50 5.6 mEq/L hardness
  • 5.6 mEq/L Ca 2.8 mMol/L CaSO4.2H20 482 mg/L
    gypsum

54
Carbo Phosphate System
10Ca212HCO3- 6H2PO4- 2H2O -gt
Ca10(PO4)6(OH)2 12CO2 2H 12H2O
55
Demonstration
  • Prepare phosphate buffer from 40 mMol/L KH2PO4
  • Add Na2HPO4 to pH 5.92
  • Phosphate buffers very commonly used to control
    pH in laboratory
  • Simulates phosphate distribution in distilled
    water mash
  • Add strong CaCl2 solution drop by drop and
    observe pH
  • pH falls gradually at first, then as precipitate
    (hydroxyl apatite) forms, more rapidly
  • This is the mechanism by which hard water
    produces acid to neutralize alkalinity
  • There is no alkalinity here (buffer made with
    distilled water)
  • Were alkalinity present, pH drop would no be so
    dramatic as some of the H released would go to
    neutralize it.

56
Part IVWater Reports
57
Water Report Key Parameters1st Aspect
  • Alkalinity
  • Measure of acid required to lower sample pH to
    4.3 buffering capacity of water
  • Indicator of amount of acid (from any source)
    required to establish proper mash pH (5.2-5.6)
  • Measure of bicarbonate content
  • Hardness
  • Measure of amount of calcium and magnesium in
    sample.
  • Mg and Ca should be measured and reported
    separately
  • Indicator of extent to which water is capable of
    offsetting its alkalinity (reaction with malt
    phosphate)
  • pH
  • Permits calculation of ion balance (quality check
    on report)
  • Permits calculation of amount of bicarbonate from
    alkalinity
  • Otherwise, not really that important

58
Water Report Key Parameters 2nd Aspect
  • Sulfate
  • Large effect on the way hops are perceived
  • High value for assertive, dry hop flavor
  • Low (15mg/L or less) for beers using a lot of
    noble hops
  • Sodium
  • Leads to salty taste in high concentrations
  • Chloride
  • Leads to salty taste in high concentration,
    pasty in very high gt300mg/L
  • Lends round, sweet quality in modest amounts
  • Iron
  • The less the better - tinny, inky, metalic
    taste
  • For Brewing, lt 0.1 mg/L EPA secondary limit lt
    0.3mg/L
  • Copper
  • Metalic taste. May indicate pipe corosion
  • Need a small amount. Yeast enzyme co factor
  • Chlorine and, in particular, Chloramine
  • Chloramine forms ppb detectable chlorphenolics
    (plastic taste)

59
Calcium
  • Most important brewing ion?
  • From dissolved limestone, gypsum
  • Important enzyme co-factor
  • Protects a-amylase from heat
  • Stimulates proteolytic and amylitic enzymes
  • Reaction with phytin lowers mash pH
  • Favors rapid, bright runoff
  • Facilitates break formation
  • Improves yeast flocculation
  • Precipitates oxalate in beer (enhanced clarity)

60
Magnesium
  • Part of hardness - half as effective as Calcium
    in RA reduction (mEq for mEq).
  • Laxative above 120 ppm esp. with SO4--
  • Sour/bitter quality at gt 30 ppm
  • Hence remove if above this level by split
    treatment (to be covered)
  • Not a problem with local (DC area) water
  • There are claims that it lowers cardiac mortality

61
Sources of Water Reports
  • Your supplier (municipality, water company)
  • Go to its website, call or visit the office
  • You are likely to get a lot of promotional
    material about DBP rule, cryptosporidium,
    industrial contaminants etc.
  • Persist until you get an inorganic report
    including alkalinity and hardness
  • Tell them that you are a brewer and this is what
    you need
  • In earlier days some suppliers were reluctant to
    release information. Rare today
  • May not be timely e.g. summary for 2008 may not
    publish until 2009
  • Test results from commercial lab (individual or
    community well owners)
  • Make sure you get an inorganic analysis
  • Organic and microbiological tests important too
    but not for your brewing needs
  • Ask other brewers (Ward Labs seems good)
  • Look in yellow pages/on web
  • Results from tests you do yourself
  • Profiles published in books, articles, papers,

62
(No Transcript)
63
April 5032.5/20 (Ca) 508.2/12.15 (Mg) 80
33.7 113.7 total hardness. Compare to April
total and calcium hardness numbers on previous
slide. Could be different methods (e.g. AAS)
samples taken on different days etc.
64
(No Transcript)
65
Imbal 100(1.4-1.1)/(1.41.1)12
66
Water Report QA Check
  • Any water report should be checked for internal
    consistency
  • Especially ones done by yourself or a lab
  • Lab often includes QA check as part of its report
  • Check based on electrical neutrality i.e. sum of
    charges on anions should equal sum on cations.
  • As relative numbers of carbonic (0),
    bicarbonate(-1) and carbonate(-2) depend on pH
    calculation gets a bit nettlesome
  • Must calculate CT, rs, fs
  • Spreadsheet on CD takes care of all this for you
  • Full instructions for use on 2nd sheet.

67
Data entry in clear cells. Calculated results
in colored cells Result in red cell should be lt
10
68
Full set of measurements from 6341 Georgetown
Pike well 30 Oct 2008
Available Water        
pH 5.84 4.300 End Point pH  
Temp for C, - for F 20.0 20.0 Temp, C  
Temp K 293.20 293.20    
pK1 6.38 6.38    
pK2 10.38 10.38    
pKw 14.16 14.16    
A 0.714      
r1 0.29 0.01    
r2 0.00 0.00    
f1 1/d 0.78 0.99 Bicarb. _at_ pHa H _at_ pHa
f2 0.22 0.01 0.049 0.050
f3 0.0000 0.0000    
f1 f2 f3 1.00 1.00    
No carb alkalinity 0.0487      
         
Alk, as CaCO3, - mEq/L 66.50      
Ca, as CaCO3, - as mg/L 56.00      
Mg, as CaCO3 - as mg/L 48.00      
Alk, mEq/K 1.33000 Gram Eq. Wt Cations Anions
22.4448 lt-- mg/L Ca mEq/L--gt 1.12 20.04 1.120  
11.6664 lt-- mg/L Mg mEq/L--gt 0.96 12.15 0.960  
Rough Carbo 5.96061      
Rough Carbonic 203.74   0.000  
Rough Bicarbonate 81.14 61.03  
Rough Carbonate 0.00 30.02  
Total Carbo, mMol/L 5.94066      
H2CO3, mg/L 203.05      
HCO3-,mg/L 80.91     1.326
CO3--,mg/L 0.00     0.000
H 0.00   0.001  
(OH)- 0.00     0.000
Sulfate. mg/L 26.50 48.04 0.552
Chloride, mg/L 5.08 35.45   0.143
Nitrate, mg/L 8.00 62.00   0.129
Nitrite, mg/L 0.36 47.00   0.008
Sodium, mg/L 8.50 22.99 0.370
Potassium, mg/L 1.76 39.10 0.045  
Fe(II), mg/L 0.02 27.92 0.001  
Fe(III), mg/L 0.01 18.62 0.001  
       
       
Free Ammonia, mg/L 0.02 32.01 0.001  
         
    Charges 2.498 2.157
    Imbal 0.341  
    Imbal 7.32  
         
Alkalinity 66.50      
Ca Hardness, as CaCO3 56.00      
Mg Hardness, as CaCO3 48.00      
         
Total Hardness, as CaCO3 104.00      
         
Residual Alkalinity 43.64 ppm as CaCO3 ppm as CaCO3  
Residual Alkalinity 0.87 mEq/L  
pH Shift RE Distilled Water 0.07      
69
Worksheet for 30 Oct 08 Analysis
70
Part VTesting Water
71
Why Discuss Testing
  • Test principals build on many of the things you
    have learned and most important test (alkalinity)
    mimics what happens in mash
  • Acid is added causing pH to drop
  • This is why alkalinity is a useful measure
  • Explanation of how test is done will enhance your
    understanding of what the parameter means
  • You may wish to do some testing yourself
  • Only way to get a feel for extent of temporal
    variation in your supply
  • Most tests relatively easily carried out with
    kits
  • Get these from www.hach.com or aquarium supply
    company
  • These things are getting expensive!

72
pH (Water Analysis Perspective)
  • Need to measure/detect end point pH in
    alkalinity titration
  • This can be done with indicator dyes but woe
    betide the color blind (your instructor)
  • Electronic means more accurate, even for non
    Daltonians
  • Electronic meters now more reliable, inexpensive,
    durable, feature laden than before
  • But be kind to your pH meter. Keep it clean and
    wet. Dont stick it into hot wort or mash!

73
pH Meter
  • Voltage E E0 (RT/F)lnH is developed across
    special glass membrane
  • E0 is voltage developed when H 1
  • R (Bolzmans) and F (Faradays) are constants
  • T is temperature (Kelvins)
  • E E0 2.303(RT/F)logH E0 - SpH
  • You (or the meter), must know E0 and S in order
    to determine pH (E0 E)/S
  • This is where standard buffers come in
  • Placing the meter in 2 solutions of known pH and
    at known temperature allows meter to calculate S
    and E0
  • Thereafter meter can adjust readings for
    temperature response of electrode (ATC)
  • But not, e.g. shift in wort pH from kettle to
    room temperature!

74
Alkalinity
alk CT(f1,a- f1,i f3,i- f3,a) - 1000(10-pHa
-10-pHi 10pHi-pKw-10pHa-pKw)
  • Defined as the number of mEq/L of acid required
    to lower pH of water sample from its initial
    value, pHi, to a reference pH, pHa
  • pHa is part of definition of alkalinity and is
    usually 4.3 in brewing
  • May be based on equivalence CTf2,a
    (1000)10-pHa
  • Analyst should report pHa. If he didnt use 4.3
  • Important because you will solve for CT in report
    quality checking, synthesis
  • Units of mEq/L (hence factor of 1000). Multiply
    by 50 for ppm as CaCO3.
  • CT total millimoles/L carbonic, bicarbonate,
    carbonate in sample
  • f s subscripted i refer to fractions at pHi
  • f s subscripted a refer to fractions at pHa
  • Kw is dissociation constant of water (pKw 14 _at_
    20C)
  • Equals sum of acid required to
  • Convert initial fractions to fractions (mostly
    carbonic) at pHa
  • Increase hydrogen ion content to 10-pHa
  • Decrease (by neutralizing to H2O) hydroxyl ion
    concentration to 10pHa-pKw

75
Alkalinity II
- Definition The number of mEq of acid which
must be added to a liter of water to bring pH
to 4.3 (IOW, to convert most carbonate and
bicarbonate to carbonic). Multiply by 50 for ppm
as CaCO3.
  • Measured by titration (addition of small
    amounts of acid
  • until pH 4.3 is reached and reporting total
    used)

- A rough indication of the amount of acid needed
in the mash per L water
Example sample pHi
Where youd Like to be in Mash tun
Where you go during titration
76
Alkalinity - Procedure
  • Add an indicator (e.g. methyl orange or
    bromcresol green-methyl red) or a pH electrode to
    100 mL sample
  • Using a buret (conventional, digital, automatic,
    eyedropper, syringe) add 0.1N (.1 mEq/L) acid
    (usually sulfuric) to sample until indicator
    turns color or pH 4.3 is reached
  • Other endpoint pH values can be used
  • Report total number of mL acid used and endpoint
    pH
  • Multiply by 50 for ppm as CaCO3.
  • Kits available Hach AL-AP 36.79 (100 tests)
  • Phenolphthalein (8.3) and Bromcresol Green-Methyl
    Red (4.3) indicators, sulfuric acid, measuring
    tube and bottle

77
Alkalinity Titration using pH Meter (Indicator
also present)
Digital Titrator Plunger, lead screw, counter
Sulfuric acid cartridge
pH electrode
Dip Tube
pH Meter
78
Total Hardness (Ca Mg)
  • Certain dyes (e.g. Eriochrome Black) are one
    color (red) in the presence of Ca or Mg and
    another color (blue) in their absence.
  • Add such a dye to 100 mL of sample with buffer to
    set pH for sharp end point
  • Titrate with a standardized strength chelating
    agent (EDTA) until the sample changes from red to
    blue.
  • Report the number of mL chelant used (it has been
    calibrated to a convenient number of mEq or ppm
    or grains or dH (German degrees) etc. hardness
    per mL)
  • This gives the total hardness (sum Ca Mg)
  • Kits available Hach HA-71A 48.25 (100 tests)
  • Test tube/bottle, EDTA, Indicator, buffer, 20 ppm
    res.

79
Calcium Hardness
  • Remove Mg from water by raising pH (add
    suitable buffer)
  • Mg 2(OH)- --gt Mg(OH)2 (insoluble gel)
  • Add dye and titrate with EDTA as before. This
    gives calcium hardness
  • Subtract from total hardness to get magnesium
    hardness
  • Kits available Hach HA-4P Total and Calcium
    Hardness 65.05 (100 tests) 20 ppm as CaCO3
    resolution
  • Test tube and bottle, 2 indicators, 2 buffers,
    EDTA
  • Doubling amount of sample halves resolution (to
    10 ppm) and halves number of tests per kit (to
    50).

80
Hardness - Colorimetric
  • Add dye to sample
  • Divide into three portions
  • Chelate Ca and Mg from first (excess EDTA)
  • Chelate Ca only from second (excess EGTA)
  • Do nothing to third.
  • Zero spectrophotometer with first - read second.
    Color depth difference is proportional to Mg
  • Zero specrophotometer with second - read third.
    Color difference is porportional to Ca
  • Add the two values for total hardness.
  • No simple kits available - requires photometer or
    spectrophotometer.

81
Chloride
  • Titration (kits available)
  • Diphenyl Carbazone forms a light pink complex
    with Hg (mercuric) ions
  • Add DPC to sample, titrate with calibrated
    mercuric nitrate.
  • Precipitate of HgCl2 forms.
  • When all Cl- has precipitated any additional Hg
    forms colored complex with diphenyl carbazone.
  • Amount of Hg(NO3)2 used to obtain color is
    proportional to amount of chloride in sample
  • Colorimetry (uses photometer)
  • Add Mercuric Thiocyanate
  • Hg(SCN)2 Cl- ---gt HgCl2 2SCN-
  • Add ferric ion solution
  • 3SCN- Fe ---gt Fe(SCN)3 (red orange)
  • Measure depth of color formed with photometer.
  • Note Nasty mercury salts used in both these - Hg
    waste

82
Sulfate
  • Barium sulfate is insoluble, Barium chloride is
    soluble.
  • Add barium chloride to sample. Barium coalesces
    with sulfate to form insoluble BaSO4
  • Special agents in test reagent keep this in
    suspension
  • Read turbidity in turbidimeter or
    spectrophotometer calibrated with standard
    solutions.
  • No kits available - requires turbidimeter or
    photometer.

83
Sodium
  • No practical chemical method
  • Atomic Absorption/Atomic Emission
    Spectrophotometry
  • Sample is vaporized into flame. Optical
    absorption (or emission) at 589.6 nm is measured.
  • Ion Selective Electrode (ISE)
  • Similar to pH electrode except that its glass
    responds to logNa rather than logH
  • Expensive (hundreds of )
  • Electrical response to calibrated standards is
    recorded (similar to pH).
  • Electrical response to sample is recorded
  • Electrode is very slow to respond (especially at
    low concentrations) so automatic (e.g. strip
    chart) recording is preferred
  • Sample response is interpolated into calibration
    curve
  • Some meters have the math built in

84
Sodium - Multiple Additions
  • mV U1 UnlogNa
  • U1 response to 1 mg/L (unknown)
  • Un response change per decade (only
    approximately known)
  • Na sample sodium concentration (what we want
    to know)
  • Place electrode in known volume, v0, of sample
    and record response
  • Add spikes i.e. known volumes v1, v2 mL of
    sodium standard solution of known strength S
    mg/mL. Then
  • mV0 Unlog(v0Na0) U1
  • mV1 Unlog(v0 Na0 S(v1)/(v0 v1)) U1
  • mV2 Unlog(v0 Na0 S(v1 v2 )/(v0 v1 v2
    )) U1
  • 3 measurements are sufficient (though more are
    better) to allow estimation of Na0, Un, and U1
  • Math is not basic (iterative non linear mmse
    estimation) but easily handled in a laptop
  • Excel Solver can do it!

85
Sodium ISE Recording Example
86
Analysis of Assymptotic mV Readings from Previous
Slide
Slope 48.4336, Intercept -148.0979 mV,
Concentration 5.8632 0.0255 mg/L rmse
0.1015 mV after 88 iterations. Un DOP 4.74
mV/decade/mV U0 DOP 7.57 mV/mV
Concentration DOP 4.48 mg/L/mV
87
Chlorine/Chloramine
  • N,N-diethyl-p-phenylenediamine (DPD) added to
    sample
  • Magenta Würster Dye formed if free chlorine is
    present
  • Depth of color measured on photometer or judged
    relative to printed color patches, color wheels
    etc.
  • Where chloramine is present it is converted to
    free chlorine first - total reading
  • Difference RE free chlorine measurement is
    chloramine
  • Kit Hach CN-66 45.29 (50 tests total 50 free)-
    0.1 ppm resolution
  • DPD, color wheel, 2 test tubes, test fixture.

88
Other Ions
  • There are tests for dozens of other ions
  • Fe(II), Fe(III), Cu, Mn, Zn, NO2, NO3, K, Al,
    SiO2, NH3 all based on similar principals
  • Kits are available for many (www.hach.com)
  • Most of these are not important in brewing unless
    well in excess of typical values
  • i.e. in excess of EPA secondary limits
  • Water tastes bad.
  • If in excess of primary limit, dont drink it or
    brew with it
  • Fe, Cu, Zn in excess may indicate corrosion
  • Zn in particular may indicate leaching from brass
    in well fittings with potential that lead is
    being extracted as well
  • Brass containing lead now prohibited in wells

89
Summary of Measurement Techniques
  • Titration
  • Addition of reagent of calibrated strength until
    an end point (color change, particular pH) is
    reached
  • Color development color depth measurement
  • By visual comparison to printed chart, color
    wheel etc.
  • By use of photometer of spectrophotometer
  • Gravimetry
  • A precipitate is formed, separated and weighed
  • A precipitate is formed and kept in suspension.
    Its ability to scatter light is mesured by a
    nephelometer or spectrophotometer
  • Electrochemistry
  • An electrode which responds to the concentration
    of a particular species of ion is placed in the
    sample.

90
Practical Considerations
  • Only the simplest tests (alkalinity, hardness,
    chorine) can be done without a lot of trouble and
    expense
  • Of limited but sufficient accuracy for brewing
  • More accurate measurements, as with pH, require
    calibration with standards
  • Chemistries age. Old chemistries can be used past
    expiration dates but standards must be employed
  • Much more involved than tolerability unless this
    is part of the hobby (or commercial operation)

91
Part VIISynthesizing Water With Desired Profile
92
Where Do I Get Profiles?
  • From textbooks, friends, articles, the internet,
    the ones on the handout CD ROM
  • Caution - not all profiles are physically
    realizeable.
  • Reporting, measurement, interpretation errors
  • Reporting of average values
  • Simple check add up all ion concentrations,
    specify a pH and calculate net electronic charge
  • Must be close to 0 (imbalance of a few )
  • Easily done with spreadsheet on CD ROM
  • Same as for evaluating quality of water reports
  • You cant get a good approximation to an
    unrealizeable profile!

93
Target Profile Burton on Trent
94
Base Water
  • Deionized (DI) water (distilled, ion exchanged
    but not by home water softener!) represents
    blank piece of paper
  • RO water is a decent approximation to DI
  • Other water can increase an ion concentration
    easily but not decrease it
  • Dilution with DI/RO water
  • Bicarbonate can be removed to some extent
  • Takes calcium and magnesium with it.
  • Modern municipal supplies generally represent a
    decent starting point

95
Source Water McLean Well
96
Approach to Synthesis
  • Simply add anything that is deficient!
  • Catch You must add salts. Ratio of calcium to
    chloride in CaCl2 is fixed! (100mg Ca35mg Cl)
  • Nevertheless you can do quite well using a few
    common salts
  • NaCl, MgSO4.7H20, NaHCO3 Source - grocery or
    drugstore
  • Table salt (dont use iodized!), epsom salts,
    baking soda
  • CaSO4.2H20, CaCO3, CaCl2.2H2O Source homebrew
    supply shop
  • Gypsum, (precipitated) chalk, calcium chloride
  • If using carbonate, bicarbonate or changing
    alkalinity you will need acid
  • This can be CO2
  • Sulfuric or Hydrochloric (not recommended FCC,
    USP, safety)
  • Math is nettlesome successive approximations by
    manipulation of salt addition amounts until
    combined error in ion concentrations is small
  • Excel Solver to the rescue!
  • Set up the problem and let the Solver do the
    work.

FCC Food Chemicals Codex i.e. approved for use
in food for human consumption
USP United States Pharmacopoeia i.e. approved
for use in drugs for humans
97
Adding an Ion from a Salt
  • Gypsum is CaSO4.2H2O GMW 172.14
  • Each millimole of 172.14 mg contains 40 mg of
    Ca and 98 mg of SO4--
  • To add, for example, 60 mg/L Ca would require
    60/40 1.5 mMol 258.2 mg gypsum for each litre
    treated
  • And you are also adding 1.598 147 mg/L SO4--
    like it or not.
  • To add 250 mg/L sulfate use 250/98 2.55 mMol
    440 mg/L
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