A 28.0g Sample of nitrogen gas combines completely with 6.0g of hydrogen gas to form ammonia. What is the mass of ammonia formed?
A 22.0g Sample of nitrogen gas combines completely with 9.0g of hydrogen gas to form ammonia. What is the mass of ammonia formed?
28.0 + 6.0 = 34.0g
ANSWERS
22.0 + 9.0 = 31.0g

If 45.98g of sodium combines with chlorine gas to form 116.89g of sodium chloride, what mass of chlorine gas is used in the reaction?
If 43.97g of sodium combines with chlorine gas to form 114.86g of sodium chloride, what mass of chlorine gas is used in the reaction?
45.98 + X = 116.89
-45.98 -45.98
X = 70.91g
ANSWERS
43.97 + X = 114.86
-43.97 -43.97
X = 70.89g

When burning 180g of glucose in the presence of
192g of oxygen, water and carbon dioxide are produced. If 108g of water is produced, how much carbon dioxide is produced?
ANSWERS
180 + 192 = 108 + X
372 = 108 + X
-108 -108
264g = X
When burning 185g of glucose in the presence of
187g of oxygen, water and carbon dioxide are produced. If 104g of water is produced, how much carbon dioxide is produced?
185 + 187 = 104 + X
372 = 104 + X
-104 -104
268g = X

A 25.3g sample of an unknown compound contains 0.8g of oxygen.
What is the percent by mass of oxygen in the compound?
(0.8/25.3) x 100
= 3%
A 29.1g sample of an unknown compound contains 0.9g of oxygen.
What is the percent by mass of oxygen in the compound?
ANSWERS
(0.9/29.1) x 100
= 3%

Magnesium combines with oxygen to form magnesium oxide. If 10.57g of magnesium reacts completely with 6.96g of oxygen, what is the percent by mass of oxygen in magnesium oxide?
ANSWERS
10.57 + 6.96 = 17.53
(6.96/17.53) x 100
= 39.7%
Magnesium combines with oxygen to form magnesium oxide. If 10.67g of magnesium reacts completely with 6.83g of oxygen, what is the percent by mass of oxygen in magnesium oxide?
10.67 + 6.83 = 17.50
(6.83/17.50) x 100
= 39.0%

When mercury oxide is heated, it decomposes into mercury and oxygen. If
28.4g of mercury oxide decomposes, producing
2.0g of oxygen, what is the percent by mass of mercury in mercury oxide?
ANSWERS
2.0 + X = 28.4
X = 26.4
(26.4/28.4) x 100
= 93.0%
When mercury oxide is heated, it decomposes into mercury and oxygen. If
28.9g of mercury oxide decomposes, producing
2.5g of oxygen, what is the percent by mass of mercury in mercury oxide?
2.5 + X = 28.9g
X = 26.4
(26.4/28.9) x 100
= 91.3%

Two unknown compounds are analyzed.
Compound I contains 5.63 g of tin and 3.37 g of chlorine, while Compound II contains 2.50 g of tin and 2.98 g of chlorine.
Find the relative mass of tin in the compounds.
ANSWERS
I
II
Mass of Tin
5.63 g
2.50 g
Mass of Cl
3.37 g
2.98 g
Mass Tin/mass Cl
1.67
.839
I/II =
1.67/.839
= 2

Two unknown compounds are analyzed.
Compound I contains 52.46 g of iron and 22.54 g of oxygen, while Compound II contains 25.19 g of iron and 32.47 g of oxygen.
Find the relative mass of iron in the compounds.
Mass of Fe
ANSWERS
Mass of O Mass Fe/Mass O
I
II
52.46 g
25.19 g
22.54 g
32.47 g
.7757
2.327
I/II =
2.327/.7757
= 3