Unit 2 Practice Quiz: Try to do this quiz without refering tothe answers. You can use your text and CD Notebook for refernece. (Answers follow)

1. Balance the following equations by "inspection"

a) ____ Sn(s) + ____F2 (g) = _____ SnF4 (s)

b) ____C3H8 (g) + ____ O2 (g) = _____CO2 (g) + ____H2O (l)

2. Determine the oxidation number for each element in the following compoundsor ions.

a) Perchloric acid, HClO4

b) sulfate ion, SO4 (-2)

c) ammonium ion, NH4+

d) dihydrogen phosphate ion, H2PO4 -

e) potassium nitrite, KNO2

3. Rewrite the following reactions to eliminate the "spectator"ions and create a balanced net ionic equation. The equation are NOT balanceas written.

a) Pb(NO3)2 (aq) + HCl (aq) = PbCl2 (s) + HNO3 (aq)

b) (NH4)2CO3 (aq) + Cu(NO3)2 (aq) = CuCO3 (s) + NH4NO3 (aq)

c) Are either one or both of these reactions an example of an oxidation -reduction reaction ?

4. Tell whether each of the following ionc salts is expected to be solublein water or not, If it is soluble, what solvated ions are in solution?

a) AgNO3, silver nitrate

b) Mg(CH3CO2)2, magnesium acetate

c) NiS, nickel (II) sulfide

5. Given the combustion reaction between ethylene gas and oxygen, checkthe equation for "balance" and indicate which element is oxidized and which one is reduced ? In this caes, what reactant is the oxidizingagent and which one is the reducing agent ?

C2H4 (g) + O2 (g) = 2 CO2 (g) + 2 H2O (g)

Answers:

1 a) Sn (s) + 2 F2 (g) = SnF4 (s)

b) C3H8 (g) + 5 O2 (g) = 3 CO3 (g) + 4 H2O (l)

2. a) HClO4 oxidation numbers H = +1, O = -2 and Cl = +7

b) SO4(-2) oxidation numbers O = -2 and S = +6

c) NH4+ oxidation numbers H = +1 and N = -3

d) H2PO4- oxidation numbers H = +1, O = -2 and P = +5

e) KNO2 oxidation numbers O = -2, K = +1 and N = +3

3. a) Net ionic equation = Pb2+(aq) + 2 Cl- (aq) = PbCl2 (s) Note: H+(aq) and NO3- (aq) are the spectator ions in this case.

b) Net ionic equation = CO3(2-) (aq) + Cu 2+ (aq) = CuCO3 (s) Here ammoniumion and nitrate ion remain in solution as"spectators".

c) neither one is and example of a redox equations. The respective oxidationnumbers of all elements remain the same as reactants as they do as products.Check it out!

4.a) Yes all nitrates are soluble. Two ions in solution, the cation isAg+ (aq) and the anion is NO3-(aq).

b) Yes acetate salts are generally soluble. Three ions in solution, one,Mg2+(aq) cation and two, CH3CO2- (aq) anions.

c) Insoluble NO ions in solutions. For some reason, many studentsdetermine a particular salt is insoluble using the guidelins but proceedto dissociate the given inslouble salt into "cations and anionsin solution" to answer the second part of the question. Don't do that,an inaoluble salt does not dissolve and does not produce ions in solutionat an appreciable level.

5.Carbon in C2H4 has oxidation # = -2 and in the product CO2 , carbonis +4, therefore carbon is oxidized in the reaction and C2H4, ethylene gas,is the reducing agent. Molecular oxygen,O2 has oxidation # = 0 by "Rule1" page 191, and oxygen in H2O is -2, therefore oxygen is reduced inthe reaction and molecular oxygen, O2 (g), is the oxidizing agent.