Problems A
181
The weight of the Ag 2 S produced is 1.322 g. How pure was the original
sample of FeS?
3. How many grams of zinc are needed to prepare 3.00 liters of hydrogen at
standard conditions? The reaction is
Zn + H 2 SO 4 -» ZnSO 4 + H 2
4. (a) How many grams of zinc are needed to prepare 3.00 liters of H 2 collected
over water at 750 torr and 26°C?
(b) How many moles of H 2 SO 4 are used?
5. What volume of O 2 at 730 torr and 25°C will react with 3.00 liters of H 2 at the
same conditions?
6. What volume of steam at 1000°C and 1 atm is needed to produce 10
s ft
3 of H 2 ,
under the same conditions, by the reaction
4H 2 O + 3Fe ± Fe 3 O 4 + 4H 2
7. What volume of C1 2 at 730 torr and 27°C is needed to react with 7.00 g of
sodium metal by the reaction
2Na + C1 2 -* 2NaCl
8. (a) How many grams of MnO 2 are needed to prepare 5.00 liters of C1 2 at 750
torr and 27°C?
(b) How many moles of HC1 are needed for the reaction? The reaction is
MnO 2 + 4HC1 -H> MnCl 2 + C1 2 + 2H 2 O
9. How much H 2 S gas at 725 torr and 25°C is needed to react with the copper in
1.5 g of CuSO 4 ? The reaction is
CuSO 4 + H 2 S -^ CuS + H 2 SO 4
10. (a) What volume of O 2 at 730 torr and 60°F is needed to burn 500 g of octane,
C 8 H 18 ?
(b) What volume of air (21% O 2 by volume) is needed to provide this amount
of O 2 ? Balance the equation before working the problem.
C 8 H 18 + O 2 ^ CO 2 + H 2 O
11. Chlorine is prepared by the reaction
2KMnO 4 + 16HC1-* 2KC1 + 2MnCl 2 + 5C1 2 + 8H 2 O
(a) What weight of KMnO 4 is needed to prepare 2.50 liters of C1 2 at standard
conditions?
(b) How many moles of HC1 are used?
(c) What volume of solution is needed if there are 12.0 moles of HC1 per liter?
(d) What weight of MnCl 2 is obtained from the reaction?
12. Nitric oxide is prepared by the reaction
1:
3Cu + 8HNO 3 ^ 3Cu(NO3) 2 ^ 2ND + 4H 2 O