# Stoichiometry Practice Problems Key 1. The Claus reactions, shown

```Stoichiometry Practice Problems Key
1.
The Claus reactions, shown below, are used to generate elemental sulfur
from hydrogen sulfide.
2H2S + 3O2  2SO2 + 2H2O
SO2 + 2H2S  3S + 2H2O
How much sulfur (in grams) is produced from 15.0 g of O2?
a.
b.
c.
d.
e.
2.
When 189.4 g of ethylene (C2H4) burns in oxygen to give carbon dioxide and
water. How many grams of CO2 are formed?
a.
b.
c.
d.
e.
3.
594.1 g
297.1 g
148.6 g
6.75 g
243.3 g
How many grams of Ca(NO3)2 can be produced by reacting excess HNO3 with
6.55 g of Ca(OH)2?
a.
b.
c.
d.
e.
4.
67.6 g
10.0 g
15.0 g
30.1 g
none of these
7.25 g
14.5 g
29.0 g
13.1 g
6.55 g
When 20.0 g C2H6 and 60.0 g O2 react:
a.
Write a balanced chemical equation.
2C2H6 + 7O2  4CO2 + 6H2O
b.
How many grams of water are formed?
29.0 g
5.
of
A 5.95 g sample of AgNO3 is reacted with BaCl2 to experimentally give 4.19 g
silver chloride. What is the percent yield of this product?
a.
b.
c.
d.
e.
6.
59.4%
70.4%
41.7%
83.5%
100%
The mineral mimetite has the formula Pb5(AsO4)3Cl. What mass % of oxygen
does it contain?
a.
b.
c.
d.
e.
38.70%
16.34%
50.32%
12.90%
1.08%
7.
A compound composed of sulfur and fluorine is found to contain 25.24% by
mass of sulfur. If the molar mass of the compound is 254.11 g/mol, what is the
molecular formula?
a.
b.
c.
d.
e.
8.
S3F8
S2F8
SF5
S2F5
S2F10
What is the molar mass of the compound formed between magnesium and
phosphorous?
Mg3P2 = 134.87 g/mol
9.
How many atoms of phosphorous are in 6.5 x 1022 formula units of the
compound in #8?
1.3 x 1023 atoms P
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