Reactions%20in%20Aqueous%20Solutions%20Chapter%207

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Reactions in Aqueous SolutionsChapter 7
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Determining Types of Reactions

• Synthesis 1 product
• Decomposition 1 reactant
• Single displacement 1 element 1 compound
  react to produce a different element a
  different compound
• Double displacement 2 compounds react to form
  two different compounds.
• Neutralization acid and base in the reactants
  water as one of the products.
• Combustion O2 as a reactant CO2 and H2O as
  the products.

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Determining the type of reaction

• Does your reaction have two (or more) substances
  combining to form one compound? If yes, then it's
  a synthesis reaction.
• 2 H2(g) O2(g) ? 2 H2O(l)
• Na(s) Cl2(g) ? NaCl(s)

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Determining the type of reaction

• Does your reaction have one compound breaking
  down to make two or more smaller substances? If
  yes, then it's a decomposition reaction.
• 2 HgO(l) ? 2 Hg(l) O2(g)
• NaHCO3(s)?Na2CO3(s) H2O(l) CO2(g)

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Determining the type of reaction

• Does your reaction start with a compound and an
  element and produce a different compound and a
  different element? If yes, then it's a single
  displacement reaction .
• CuCl2(aq) Mg(s) ? MgCl2(aq) Cu(s)
• KCl(aq) F2(g) ? KF(aq) Cl2(g)

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Determining the type of reaction

• A double displacement reaction starts with two
  compounds and makes two new compounds.
• FeCl3(aq)MgSO4(aq)?Fe2(SO4)3(s)MgCl2(aq)
• NaCl(aq) AgNO3(aq) ? NaNO3(aq) AgCl(s)

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Determining the type of reaction

• Does your reaction have an acid as one of your
  reactants and water as one of the products? If
  yes, then it's an acid-base or neutralization
  reaction.
• HCl(aq) NaOH(aq) ? NaCl(aq) H2O(l)
• acid base
• Ca(OH)2(aq) H3PO4(aq) ? H2O(l) Ca3(PO4)2(aq)
• base acid

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Determining the type of reaction

• Does your reaction have oxygen as one of it's
  reactants and carbon dioxide and water as
  products? If yes, then it's a combustion
  reaction.
• CH4(g) O2(g) ? CO2(g) H2O(g)
• C8H18(g) O2(g) ? CO2(g) H2O(g)

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More Examples
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Determining Products of Reactions

• To predict the products for any equation, you
  must first determine the type of reaction by
  looking at the reactants.
• Synthesis 1 product
• Decomposition 1 reactant
• Combustion O2 as a reactant CO2 and H2O as
  the products.

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Reaction Prediction

• 2 or more reactants and youre told that theres
  only one product synthesis
• When writing the products, you must look at the
  charges of the ions. The equations will most
  likely not be balanced!
• Example Al(s) Br2(l) ?
• Example Ca(s) N2(g) ?

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Reaction Prediction

• 1 reactant decomposition (if you have a
  decomposition, then it will be a compound
  splitting up into its elements)
• Remember the 7 diatomic molecules and to write
  them with a 2 if by themselves.
• Example CCl4(l) ?
• Example Mg3N2(s) ?

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Reaction Prediction

• hydrocarbon (compound with C H) O2
  combustion (always have CO2 and H2O as your
  products)
• Example CH4(g) O2(g) ?
• Example C3H8O(g) O2(g) ?

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More Examples

• C8H18 O2 ?
• Ba(NO3)2 ?
• Mg O2?

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Reaction Prediction Part 2

• Single displacement 1 element 1 compound
  react to produce a different element a
  different compound
• Double displacement 2 compounds react to form
  two different compounds.
• Neutralization acid and base in the reactants
  water as one of the products.

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Reaction Prediction

• 1 element 1 compound single displacement
  (replacement)
• In the products, you cant have two positive ions
  or two negative ions combined together, only one
  positive and one negative ion.
• Example Mg(s) Zn(NO3)2(aq) ?
• Example Cl2(g) KF(aq) ?

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Reaction Prediction

• 2 ionic compounds double displacement
  (replacement). As before, you cant put two
  positive ions or two negative ions together.
• Example
• AgNO3(aq) NaCl(aq) ?
• Example
• Fe2(SO4)3(aq) Na3PO4 (aq)?

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Reaction Prediction

• 1 acid (starts with H) 1 base (ends with OH)
  acid-base or neutralization (always makes H2O as
  one product)
• Water gets rid of all hydrogen and hydroxide
  ions. The other compound comes from the leftover
  ions.
• Example HCl(aq) KOH(aq) ?
• Example Ca(OH)2(aq) H2SO4(aq)?

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More Examples
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Solubility

• If a substance is an aqueous solution (aq), it is
  a substance that dissolves in water, or is
  soluble in water.
• If a substance is insoluble, it will not dissolve
  in water, and when formed as the result of a
  reaction will appear as a precipitate (solid).
• If a substance is slightly soluble or partially
  soluble in water, only a small portion of that
  substance will dissolve in water.

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Electrolytes

• Electrolyte solution that that has the ability
  to conduct electricity.
• When an ionic compound dissolves in water it
  separates into ions and is called a strong
  electrolyte, for example NaCl dissolved in water.
• Compounds that dissolve in water but do not
  conduct electricity are called nonelectrolytes,
  for example, sugar dissolving in water.

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Figure 7.3 Solubilities of common compounds.
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Solubility Examples

• In order for a compound to be an aqueous
  solution, one of the ions (either the positive
  ion or the negative ion) must be soluble in
  water, but not both
• FeCO3

• Ca(NO3)2
• CuOH
• CaCl2
• (NH4)2SO4
• Zn3(PO4)2
• SrO

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Precipitation Reactions

• In all precipitation reactions, the ions of one
  substance are exchanged with the ions of another
  substance when their aqueous solutions are mixed
• At least one of the products formed is insoluble
  in water
• KI(aq) AgNO3(aq) ? KNO3(aq) AgI?s?

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Process for Predicting the Products ofa
Precipitation Reaction

• Here is what weve already covered
• Determine what ions each aqueous reactant has
• Exchange Ions
• () ion from one reactant with (-) ion from other
• Balance Charges of combined ions to get formula
  of each product

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Process for Predicting the Products ofa
Precipitation Reaction

• Determine Solubility of Each Product in Water
• solubility rules/table
• if any of the products are insoluble or slightly
  soluble, a precipitate will form
• If all substances formed are aqueous solutions
  then no precipitate will form and there is really
  no reaction, just ions floating around in water.

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Figure 7.1 The precipitation reaction that
occurs when yellow potassium chromate,
K2CrO4(aq), is mixed with a colorless barium
nitrate solution, Ba(NO3)2(aq).
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Figure 7.4 Precipitation of silver chloride
occurs when solutions of silver nitrate and
potassium chloride are mixed.
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Example Problems

• Predict the products given each of the following
  reactants. Also denote which compound forms a
  precipitate
• Cu(NO3)2(aq) KOH(aq) ?
• FeCl3(aq) Mg3(PO4)2(aq) ?
• NaBr(aq) KNO3(aq) ?

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Ionic Equations

• Equations which describe the chemicals in aqueous
  solution and their product molecules are called
  molecular equations
• KCl(aq) AgNO3(aq) ? KNO3(aq) AgCl(s)
• equations which describe the actual ions and
  molecules in the solutions as well as the
  molecules of solid, liquid and gas not dissolved
  are called ionic equations
• K(aq)Cl-(aq)Ag(aq)NO3-(aq)?K(aq)NO3-(aq)Ag
  Cl(s)
  

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Ionic Equations

• ions that are both reactants and products are
  called spectator ions
• K(aq)Cl-(aq)Ag(aq)NO3-(aq)??K(aq) NO3-
  (aq) AgCl(s)
• an ionic equation in which the spectator ions
  are dropped is called a net ionic equation
• Cl- (aq) Ag (aq) ??AgCl(s)

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Example Problems

• Write the molecular, complete ionic and net ionic
  equations for the following equations. Also
  identify any spectator ions
• Cu(NO3)2(aq) KOH(aq) ? KNO3(aq) Cu(OH)2(s)

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Example Problems

• Write the molecular, complete ionic and net ionic
  equations for the following equations. Also
  identify any spectator ions
• Fe2(SO4)3(aq)Pb(ClO3)2(aq)?Fe(ClO3)3(aq)PbSO4(s)
  

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Example Problems

• Write the molecular, complete ionic and net ionic
  equations for the following equations. Also
  identify any spectator ions
• KCl(aq) (NH4)2SO4(aq) ? K2SO4(aq) NH4Cl(aq)