Mass to Mass Stoichiometry

January 3, 2016

1. Carbon dioxide is produced in the reaction between calcium carbonate and hydrochloric
acid.
a. Write the balanced equation for this reaction.
b. How many grams of calcium carbonate would be needed to react completely with
15.0g of hydrochloric acid?
c. How many grams of carbon dioxide would be produced in this reaction?
d. How many grams of calcium chloride would be formed at the same time?
2. Sulfur dioxide may be catalytically oxidized to sulfur trioxide.
a. Write the balanced equation for this reaction.
b. How many grams of sulfur dioxide could be converted by this process if 100.0g of
oxygen are available for the oxidation?
3. Lightning discharges in the atmosphere catalyze the conversion of nitrogen to nitric
oxide.
a. Write the balanced equation for this reaction.
b. How many grams of nitrogen would be required to make 25.0g of nitric oxide in this
way?
4. Iron (III) oxide many be reduced to pure iron either with carbon monoxide or with coke
(pure carbon). Suppose that 150.0kg of ferric oxide are available.
a. Write both balanced equations for this reaction.
b. How many kilograms of carbon monoxide would be required to reduce the oxide?
c. How many kilograms of coke would be needed?
d. In each case, how many kilograms of pure iron would be produced?
5. Zinc metal will react with either hydrochloric or sulfuric acid to produce hydrogen gas.
a. Write both balanced equations for this reaction.
b. If 50.0g of zinc are to be used in the reaction, how much HCl would be needed to
completely react with all of the zinc?
c. If 50.0g of zinc are to be used in the reaction, how much H2SO4 would be needed
to completely react with all of the zinc?
d. How much hydrogen gas (in grams) would be produced using HCl?
e. How much hydrogen gas (in grams) would be produced using H2SO4?

6. Calcium phosphate, silicon dioxide, and coke may be heated together in an electric
furnace to produce phosphorus, as shown in the following equation.
2Ca3(PO4)2 + 6SiO2 + 10C  6CaSiO3 + 10 CO + P4
a. In this reaction, how many kilograms of calcium phosphate would be needed to
make 100.0kg of phosphorus?
b. How much calcium silicate would be formed as a by-product?
c. How much sand would be used up in this same reaction?
7. Phosphoric acid is produced in the reaction between calcium phosphate and sulfuric acid.
a. Write the balanced equation for this reaction.
b. How much of the phosphoric acid would be produced from 55g of the calcium
phosphate?
c. What other product is formed?
d. In what quantity is the other product produced?
8. Phosphine, PH3, is formed when calcium phosphide is added to water.
a. Write the balanced equation for this reaction.
b. How many grams of phosphine can be obtained from 200.0g of calcium phosphide?
c. How many grams of the other product are formed?
9. Coke will reduce hot arsenious oxide to pure arsenic (As4).
a. Write the balanced equation for this reaction.
b. How much coke would be required to completely reduce 500.0kg of the oxide?
c. How much arsenic is recovered from this reaction?
10. How much iron will be required to release all of the antimony from 10.0g antimony
sulfide?
a. Write the balanced equation for this reaction. (Ferrous sulfide is formed).
b. How much antimony is obtained in this reaction?
11. Sodium tetraborate is produced according to the following reaction.
4H3BO3 + 2NaOH  7H2O + Na2B4O7
a. How much boric acid is needed to make 150kg of sodium tetraborate?
12. Calcium oxide can be prepared by heating calcium in oxygen.
a. Write the balanced equation for this reaction.
b. How much calcium would be needed to make 15.0g of calcium oxide in this way?
c. If the calcium oxide were prepared by heating calcium carbonate…
i. Write the balanced equation for this reaction.
ii. How much of the carbonate would be required to produce the 15.0g of the
oxide?

d. If the calcium oxide were to be obtained by the heating of calcium hydroxide…
i. Write the balanced equation for this reaction.
ii. How much hydroxide would be needed to obtain the 15.0g?
iii. If 15.0g of calcium oxide was allowed to react with the water, what amount
of calcium hydroxide would be produced?
13. How much magnesium sulfate is needed to completely react with 145g of sodium
chloride?
a. Write the balanced equation for this reaction.
b. How much sodium sulfate could be produced by this reaction?
14. In nature, carbon dioxide in the atmosphere reacts with calcium hydroxide to produce
calcium carbonate. This calcium carbonate will react with carbonic acid (carbon dioxide
and water) to form calcium bicarbonate.
a. Write both balanced equations for the reactions.
b. What mass of calcium bicarbonate would eventually be produced by the action of
carbon dioxide on 1.0g of calcium hydroxide?
15. Hard water, containing calcium bicarbonate as hardness, may be softened by adding
sodium hydroxide. Sodium carbonate, calcium carbonate, and water all are formed in the
reaction.
a. Write the balanced equation for this reaction.
b. What mass of sodium hydroxide would be needed to react with all the calcium
bicarbonate formed in problem 14?
16. Permanent hard water contains calcium sulfate and can be softened by the addition of
sodium carbonate.
a. Write the balanced equation for this reaction.
b. What amount of sodium carbonate would have to be added to react with 1.0kg of
calcium sulfate?
17. Beryllium hydroxide is amphoteric. It reacts with hydrochloric acid to give beryllium
chloride. It also reacts with sodium hydroxide to give sodium beryllate (Na2BeO2).
a. Write both balanced equations for these reactions.
b. If 20.0g of beryllium hydroxide are available, how many grams of beryllium
chloride can be prepared?
c. How many grams of sodium beryllate could be made?
d. How many grams of hydrochloric acid would be required for this reaction?
e. How many grams of sodium hydroxide would be required for this reaction?
18. The rare earth element terbium may be prepared by the electrolysis of its fused chloride
(valence of terbium= 3).
a. Write the balanced equation for this reaction.

b. How many grams of the chloride would be needed to supply 1.00g of the pure
metal?
19. Gadolinium, europium, and samartium may all be prepared in the same way as terbium. All
of these elements have a valence of 3.
a. Write the balanced equation for all three equations.
b. How much of the chloride would be required, in each case, to produce 10.0ug of the
pure element?
ii. Europium
iii. Samartium
20. The metals: manganese, chromium, indium, and tin are all prepared by the reduction of
their oxides with carbon.
a. Write the balanced equation for all 5 reactions (see i-v below).
b. How much carbon will be needed to reduce 100.0kg of each of the following oxides?
i. Manganese dioxide
ii. Chromium (III) oxide
iii. Indium oxide
iv. Tin (II) oxide
v. Tin (IV) oxide
21. Lanthanum and cerium may be obtained in the free state by fusing their respective
chlorides with metallic potassium.
a. What amount of the chloride is needed to produce 1.0kg of lanthanum?
b. What amount of the chloride is needed to produce 1.0kg of cerium?
22. Gold will dissolve in the acid mixture known as aqua regia according to the following
reaction: Au + HNO3 + 3HCl  AuCl3 + NO + 2H2O
a. How much aruic chloride will be produced in this reaction when one starts with
5.0mg of gold?
b. How much nitric acid must be added initially to dissolve all this gold?
23. How many kg of coke (carbon) are needed to reduce 100.0kg of lead monoxide to free