CHM 1045 Fall, 2011
Test 2
Name (print)___________________
Show your work for complete (and partial) credit. Report your answers to the correct
number of significant figures and use units where appropriate. All chemical equations
should balance; indicate phases. NA=6.022x1023
1. Balance the following equation.
____AlCl3(aq) + ____Pb(NO3)2(aq) → ____Al(NO3)3(aq) + ____PbCl2(s)
2. What is the mass of a sample of glucose (C6H12O6, 180.16g/mol) that contains 1.250 x
1021 carbon atoms.
3. In lab, a student reacted (by heating) elemental iron with excess elemental sulfur. A
0.558g sample of Fe produced 0.879g of the sulfide. From this information, calculate
the empirical formula for the sulfide of iron.
4. An organic compound containing C, H, and O was combusted to produce CO2 and
H2O. Combustion of 138mg of the compound produced 264mg of carbon dioxide and
162mg of water. What was the percent by mass of hydrogen in the organic
compound?
5. A sample of a hydrocarbon, a compound containing only carbon and hydrogen, was
combusted for elemental analysis. A 6.014mg sample of the compound produced
17.60mg of CO2 (44.01g/mol) and 10.81mg of H2O. What is the empirical formula
for the hydrocarbon?
6. In the reaction 2Mg(s) + O2(g) → 2MgO, what is the maximum mass of MgO
(40.304g/mol) that can be produced by the reaction of 25.0g of each reactant? Note:
this is a limiting reactant problem.
7. Give the net ionic equation for the following equation.
2HC2H3O2(aq) + Mg(s)  Mg(C2H3O2)2(aq) + H2(g).
8. What acid/base reaction has as its products water and Mg(NO2)2?
9. Given the following chemical equation, what can you say about the solubility of all
four compounds? Check a box for each compound.
CaCl2(aq) + 2AgNO3(aq) → 2AgCl(s) + Ca(NO3)2(aq)
Compound
Soluble
Insoluble
Not enough info
calcium chloride
calcium nitrate
silver chloride
silver nitrate
10. In the net ionic reaction Cu(s) + 2Ag+(aq)  Cu+2(aq) + 2Ag(s),
____ is oxidized to ____ and ____ is reduced to ____.
11. Give a specific example of a strong acid (name or formula).
12. Provide the oxidation number of each of the underlined species.
a) MnO4 b) H2SO4
c) ZnCl2
d) NH4+
e) Cl2
13. Given that aluminum is above magnesium on the activity series, predict the products
of the following reactions. If no reaction will occur, write ‘n.r.’.
a) 2Al(s) + 3Mg(s) →
b) 2Al(s) + 3Mg(NO3)2(aq) →
c) 2Al(NO3)3(aq) + 3Mg(s) →
d) 2Al(s) + 3Mg+2(aq) →
14. What can you deduce, if anything, concerning the relative positions of zinc and
magnesium on the activity series based on the following information (the ‘n.r.’)?
Please explain how you reached your conclusion.
Zn(s) + Mg(NO3)2(aq) → no reaction
The following information applies to the next four questions.
Compound: CaCl2
Ca(NO3)2 AgCl
AgNO3
f.w.(g/mol): 110.99
164.09
143.321
169.87
CaCl2(aq) + 2AgNO3(aq) → 2AgCl(s) + Ca(NO3)2(aq)
15. How many mols of silver chloride is 5.253g of silver chloride?
16. What mass of CaCl2 is required to form 5.253g of silver chloride?
17. An impure sample of CaCl2(s) weighing 2.393g was dissolved in 100.mL of water.
Excess 1.30M AgNO3(aq) was added to completely react the CaCl2(aq). The AgCl
precipitate was filtered, dried, and weighed. It weighed 5.253g. What was the purity
of the original CaCl2 sample?
18. What volume of 0.325M CaCl2(aq) would be required to completely react 20.0mL of
0.325M AgNO3(aq)?
Mg(s) + 2HCl(aq) → H2(g) + MgCl2(aq) (next two questions)
19. What type of chemical reaction is this?
20. What mass of magnesium will react with 125mL of 0.225M HCl(aq)?
5 points extra credit:
Compound: KClO3
KCl
O2
NaNO3
AgCl
AgNO3
f.w.(g/mol): 122.549
74.551
31.9988
84.995
143.321
169.87
A sample containing KClO3(s) and NaNO3(s) weighing 3.081g was heated to decompose
the KClO3 to KCl(s) and O2(g). The oxygen escapes. The NaNO3(s) does not decompose.
Using the following information, calculate the mass percentage of the NaNO3(s) in the
original sample. Use either a) or b), but not both.
a) After heating, the sample weighed 2.176g.
b) After heating, the sample was dissolved in distilled water and excess
AgNO3(aq) was added. A precipitate formed. The precipitate was filtered, dried,
and weighed. It weighed 2.703g.