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Chemical Calculations
1. 0.25 moles of HNO3 are reacted according to the following equation:
3CdS + 8HNO3 → 3Cd(NO3)2 + 2NO + 3S + 4H2O
a) how many moles of CdS are reacted? [0.094moles]
b) how many moles of the gas NO are produced? [0.0625moles]
c) how many grams of NO are produced? [1.875g]
d) how many liters of NO are produced at STP? [1.4L]
e) how many grams of H2O are produced? [ 2.25g]
2. 31.6g of K2SO3 are reacted according to the following equation:
5K2SO3 + 2KMnO4 + 3H2SO4 → 6K2SO4 + 2MnSO4 + 3H2O
a) how many moles of KMnO4 are required for the reaction? [0.08moles]
b) how many grams of KMnO4 are required for the reaction? [ 12.6g]
c) how many moles of MnSO4 are produced? [ 0.08moles]
d) how many grams of MnSO4 are produced? [12.1g]
3. 16.0g of S are produced by the reaction:
9H2S + 3K2Cr2O7 + 8H3PO4 → 9S + 6CrPO4 + 2K3PO4 + 21H2O
a) how many moles of S are produced? [ 0.5moles]
b) how many moles of CrPO4 are produced? [ 0.33moles]
c) how many grams of CrPO4 are produced? [48.51g]
d) how many moles of H2S are reacted? [0.5moles]
e) how many grams of H2S are reacted? [ 17g]
f) how many grams of H2O are produced? [21g]
4. 11.2 liters of the gas C4H10 are burned completely in air at STP. The unbalanced reaction is:
C4H10 + O2 → CO2 + H2O(g)
a) how many moles of C4H10 reacted? [0.5moles]
b) how many liters of CO2 are produced at STP? [ 44.8L]
c) how many liters of O2 are reacted? [72.8L]
d) how many grams of CO2 are produced? [88g]
5. 0.10 moles of Al are mixed with 0.25 moles of HCl. The unbalanced reaction is as follows:
Al + HCl → H2 + AlCl3
a) how many moles of Al and HCl actually react? [ 0.25mol HCl, 0.083mol Al]
b) is the Al or the HCl present in excess? By how much? [ 0.017moles Al]
c) how many grams of AlCl3 are produced? [ 11.125g]
d) how many liters of H2 are produced at STP? [ 2.8L]
6. 27.0g of Al is mixed with 294g of pure H2SO4. The unbalanced reaction goes as follows:
Al + H2SO4 → Al2(SO4)3 + H2
a) how many grams of Al and H2SO4 actually react? [27g Al, 147g H2SO4]
b) is the Al or the H2SO4 present in excess? By how much? [147g H2SO4]
c) how many grams of Al2(SO4)3 are produced?
[171g]
d) what volume of H2 is produced at STP? [33.6L]
7. H2SO4 may be manufactured from iron pyrites (FeS2) by the following three step reaction:
4FeS2 + 11O2 → 2Fe2O3 + 8SO2
2SO2 + O2 → 2SO3
SO3 + H2O → H2SO4
How many grams of pure H2SO4 can be produced by reacting 30.0g of FeS2? [49g]
For questions # 8-15, SHOW ALL YOUR WORK and include a balanced chemical equation when
necessary!
8. What mass of ammonium chloride can be produced from the synthesis reaction of 3.66g of ammonia gas,
NH3, with sufficient HCl? If 10.5g of ammonium chloride were actually obtained experimentally, what is
the percent yield for the reaction?
9. In the decomposition of sulfuric acid to water and sulfur trioxide, how many grams of sulfuric acid were
reacted if 42.56 grams of sulfur trioxide were produced?
10. In the double displacement reaction between lead (II) nitrate with sodium chromate, how many grams of
each reactant were used if 12.88g of lead (II) chromate were produced? How many grams of the other
product were produced? Is the law of conservation of mass upheld in this reaction?
11. What mass of water vapor is produced if 648g of liquid heptane, C7H16, is completely burned at STP?
12. How many mL of NH3 are produced during a synthesis reaction with 47.1L of nitrogen gas and sufficient
H2? How many liters of hydrogen gas are produced?
13. The reaction of hydrazine, N2H4, and hydrogen peroxide, H2O2, produces nitrogen gas and water. How
many molecules of water and nitrogen gas will be produced from the reaction of 9.12 X 1023 molecules of
hydrazine and 59.9g of hydrogen peroxide? How many grams of excess reagent will remain?
14. In a double displacement reaction, 101g of zinc carbonate are available to react with 69.8g of lithium
phosphate. How many grams of each product form and how many grams of the excess reagent will
remain?
15. Iron(III) oxide forms from the reaction of oxygen gas and iron. When 199L of oxygen gas are available to
react with 3.68 X 1024 atoms of iron, how many grams of product form? How many moles of excess
reagent remain?