Mass is a measure (a numerical quantity) of how much matter is present.

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What is mass?

• Mass is a measure (a numerical quantity) of how
  much matter is present.

• Atoms are made up of protons and neutrons and
  each one has a mass of 1 mass unit. (Like grams
  but much, much smaller)

For Example

• Mercury (Hg) atoms consist of 80 protons and 120
  neutrons and weigh 200 mass units each.

• Lead (Pb) atoms consist of 82 protons and 125
  neutrons and weigh 207 mass units each.

?Lead atoms weigh more than mercury atoms because
they contain more matter.
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Hg
Pb
0.0
- - - - -
- - - - -
11.3
0.0
13.5

• Both boxes have a volume of 1 cm3

• Fill the boxes up with their corresponding atoms.

• The mercury box has a larger mass (even though
  mercury atoms dont weigh as much as lead)
  because the mercury atoms are packed in more
  tightly.

?Density is a measure of how much matter is
stuffed into a particular volumemost often 1 mL
or 1 cm3.
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There are only two types of substances
A compound is a substance that has two or more
types of atoms in fixed proportions.
An element is a substance that has only one kind
of atom.
Matter anything that has mass and takes up space
Substance matter that has a uniform and
unchanging composition. (i.e. you can write a
formula for it)
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Law of Definite Proportions
A chemical compound always has the same ratio of
elements (ex 2H and 1 oxygen in H2O).
Given One gram of water contains 0.11 g of
hydrogen and 0.89 g of oxygen.
(11 hydrogen, 89 oxygen)
How many grams of hydrogen and oxygen would be in
10 g of water?
1.1 g of hydrogen, 8.9 g of oxygen
In 59 grams of water?
6.5 g of hydrogen, 52.5 g of oxygen
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Substances are identified by their...
Physical
Chemical properties
and
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Substances are identified by their...
Physical
Chemical properties
and
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Physical properties can be observed and measured
WITHOUT permanently changing the material.
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Chemical properties can only be observed or
measured by PERMANENTLY CHANGING the material.
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Physical property Odor depends upon molecular
shape
Thus, a change in odor indicates that the
substance has been changed into a new substance
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Extensive properties depend upon the amount of
matter that is present.
Examples total mass, volume, length
Intensive properties do not depend upon the
amount of matter that is present.
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Physical changes change the appearance of the
substance WITHOUT changing the substances
formula.
Chemical changes result in the formation of a new
substance (the formula changes).

• FIVE INDICATORS OF CHEMICAL CHANGE
• Gas evolution (bubbles)
• Color or odor change
• Energy given off (flames)
• Temperature change
• Precipitate (a solid) formation

It is VERY important to know these!!!
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Chemical or physical change?
1. When heated, a substance goes from a liquid to
a gas. 2. When heated, the color of a substance
changes from blue to white. 3. When heated, a
substance burns. 4. When hit with a hammer, a
substance explodes.
PHYSICAL!
CHEMICAL!
CHEMICAL!
CHEMICAL!
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Chemical or physical change?
5. When hit with a hammer, a substance
flattens. 6. When hit with a hammer, a
substance breaks apart into smaller
pieces. 7. When water is added to a blue
liquid, it changes to a lighter blue. 8. When a
clear liquid is added to a blue liquid, a white
solid is formed.
PHYSICAL!
PHYSICAL!
PHYSICAL or CHEMICAL!
CHEMICAL!
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Chemical or physical change?

• When water is heated, small bubbles form on the
  bottom of the container.
• When water is added to concrete mix, the water
  begins to steam.
• 11. When water is added to dry sand, bubbles are
  observed coming up from the sand.
• 12. When water is added to a metallic solid, the
  metal melts and smoke is given off.

PHYSICAL!
CHEMICAL!
PHYSICAL!
CHEMICAL!
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Conservation of Mass Practice Problems
23 g of sodium metal is reacted with 35 g of
chlorine gas to form sodium chloride as its only
product. What was the weight of the sodium
chloride that was formed?
Reactants
Products
Sodium Chlorine
Sodium chloride
23 g
35 g

58 g

Law of conservation of mass matter is neither
created nor destroyed during a physical or
chemical change
or.What goes in must come out.
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Conservation of Mass Practice Problems
100 g of lard is reacted with 50 g of lye to form
glycerin and soap. How much soap was formed if 25
g of glycerin was produced?
Reactants
Products
Lard lye
Glycerin soap
100 g

50 g

25 g

125 g
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Extensive properties depend upon the amount of
matter that is present.
Examples total mass, volume, length
Intensive properties do not depend upon the
amount of matter that is present.
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Mixture a combination of two or more
substances. The composition of mixtures is
variable.
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Heterogeneous mixture a mixture in which the
physical properties are different in different
parts of the mixture.
heterogeneous
Homogeneous mixture a mixture in which the
physical properties are the same throughout.
soluble dye
A solution
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Types of solutions
Gas/gas
Air is 78 N2 and 21 O2
Gas/liquid
Carbonated sodas are made by dissolving CO2 gas
in water
Liquid/liquid
Vinegar is 5 acetic acid, 95 water
Solid/liquid
Sports drinks are 0.1 NaCl, 5 sugar and 94.9
water.
Solid/solid
8 carat gold is a solid solution of Cu, Ag and Au
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Viscosity a fluids resistance to flow.

• Viscous (which sounds like mucus) fluids have a
  high viscosity.

• Viscosity

as temperature
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Separating Mixtures
Mixtures can be separated by taking advantage of
differences in physical properties.
Filtration a porous barrier is used to separate
a solid from a liquid. The filter can only
separate out particles of solid that are LARGER
than the pores through the filter.
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Distillation separation of substances by
differences in boiling point.
The substance with the lower boiling point will
distill off first.
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Crystallization formation of a pure solid
substance from a solution containing the
dissolved substance.
Sodium acetate in water
p-dichlorobenzene in chloroform
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Chromatography separates two dissolved
substances by their solubility in the solvent.
The more soluble substance travels faster up the
stationary phase.
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or.What goes in must come out.
Ex 1 23 g of sodium metal is reacted with 35 g
of chlorine gas to form sodium chloride. How much
sodium chloride was formed?
23 g sodium 35 g chlorine
58 g of sodium chloride
Ex 2 56 g of iron reacts with oxygen to form 80
g of iron oxide. How many grams of oxygen were
used in the reaction?
56 g iron x g of oxygen
80 g of iron oxide
x 24 g of oxygen
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Ex 1 A sample of water contains 2 g of hydrogen
and 16 g of oxygen. What is the mass of hydrogen
and oxygen in water?
Ex 2 A compound containing only carbon and
oxygen is 27 carbon. How many grams of oxygen
are present in a 100 g sample of the compound?

• If 27 of the compound is carbon, then 73 of the
  compound is oxygen.

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Hydrates a crystalline material that contains a
fixed percentage of water molecules within its
crystal structure.
An anhydrous crystal contains no water
Solids can have a variable amount of water
adsorbed onto their surfaces.
A crystal hydrate has a constant amount of water
molecules within its crystal lattice.
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Ex 1 243 g of barium chloride dihydrate (BaCl22
H2O) are heated until the compound is anhydrous.
What is the final weight of the compound if the
hydrate is 15 water?
15 of compound is water 85 of compound is
anhydrous crystal ?
0.85 (243 g) 207 g
Ex 2 141 g of a hydrate are heated strongly
until a constant weight of 60 g is obtained. What
was the water in the hydrate?
Mass of water 141 g hydrate 60 g anhydrous
81 g of water