Answer all of the following questions. Each question
will have two parts—writing the balanced chemical equation
answering a question about the reaction. Coefficients in the balanced chemical equation must be in the lowest whole-
number ratio. Do not include formulas for substances that remain unchanged during the reaction. Unless otherwise
noted, assume all the reactions occur in aqueous solution. If a substance is extensively ionized and therefore present as
ions in solution, write its formula as ions
a). Excess sodium hydroxide is added to an aluminum
sulfate solution. Which species behaves as a Lewis acid in
b). Dichlorine heptaoxide is mixed with water. What is the oxidation number of the chlorine in the product.
c). A lead(II) nitrate solution is mixed with ammonium sulfate solution. Which ions, if any, are spectator ions in this reaction?
d). Solid manganese(IV) oxide is added to concentrated hydrochloric acid. What is the oxidation number of the species being oxidized before and after the reaction takes place?
a] Al2(SO4)3 (aq) + 6NaOH (aq) -> 3Na2SO4 (aq) + 2Al(OH)3 (s)
Net ionic equation :
2Al 3+ (aq) + 6OH- (aq) -> 2Al(OH)3 (s)
Lewis acid = Al+3
Lewis acid = A species that accepts electron pair is called Lewis Acid
b] Cl2O7 + H2O → 2HClO4
Cl oxidation number = +7
c] Molecular equation:
Pb(NO3)2 (aq) + [NH4]2SO4 (aq) -----> PbSO4 (s) + 2NH4NO3 (aq)
Pb2+ (aq) + 2NO3- (aq) + 2NH4+ (aq) + SO42- (aq) -----> PbSO4 (s) + 2NH4+ (aq) + 2NO3- (aq)
Pb2+ (aq) + SO4 2- (aq) -----> PbSO4 (s)
NH4+ and NO3- are spectator ions since NH4NO3 is soluble.
d] 4 HCl (aq) + MnO2(s) --> 2H2O (l) + MnCl2 (aq) + Cl2 (g)
Cl- is oxidised
OXidation number before oxidised of Cl is -1
Oxidation number after oxidised is 0
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