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Practice Questions
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7.1 The Mole
 
7.2 Percent Composition of Compounds
 
7.3 More Complex Stoichiometric Calculations
 
7.4 Limiting Reagents
 
 
7.5 Chemical Yields
 
7.6 Practice Questions
 
7.7 Explanations
 
Practice Questions
1. How many moles of hydrogen sulfide are contained in a 35.0 g sample of this gas?
(A) 1.03 mol
(B) 2.06 mol
(C) 6.18 mol
(D) 9.45 mol
(E) 11.3 mol
2. What is the molar mass of ethanol (C2H5OH)?
(A) 34.2
(B) 38.9
(C) 46.1
(D) 45.1
(E) 62.1
3. Ammonia can be produced by the reaction of nitrogen and hydrogen gas. Suppose the reaction is carried out starting with 14 g of nitrogen and 15 g of hydrogen. How many grams of ammonia can be produced?
(A) 17.04 g
(B) 34.08 g
(C) 51.1 g
(D) 85.2 g
(E) 102 g
4. How many atoms of hydrogen are present in 12.0 g of water?
(A) 1.11023
(B) 2.01023
(C) 4.01023
(D) 8.01023
(E) 4.81024
5. Which compound contains the highest percent by mass of hydrogen?
(A) HCl
(B) H2O
(C) H3PO4
(D) H2SO4
(E) HF
Statement I Statement II
6. In a balanced equation, the number of moles of each substance is equal.   BECAUSE   Once the limiting reagent has been consumed, the reaction can no longer continue.
7. A hydrocarbon (a compound consisting solely of carbon and hydrogen) is found to be 96% carbon by mass. What is the empirical formula for this compound?
(A) C2H
(B) CH2
(C) C3H
(D) CH3
(E) C4H
8. An unknown compound contains the elements C, H, and O. It is known to contain 48% C and 4.0% H by mass. The molar mass of this compound has been determined in the lab to have a value of 200. The molecular formula for this compound is
(A) C2H3O2
(B) C4H6O4
(C) C4H4O3
(D) C8H3O6
(E) C8H8O6
9. When 7.0 g of ethene (C2H4) burns in oxygen to give carbon dioxide and water, how many grams of CO2 are formed?
C2H4 + 3O22CO2 + 2H2O
(A) 9.0 g
(B) 22 g
(C) 44 g
(D) 82 g
(E) 180 g
10. Consider the reaction below. What mass of CF4 is formed by the reaction of 8.00 g of methane with an excess of fluorine?
CH4(g) + 4F2(g)CF4(g) + 4HF(g)
(A) 19 g
(B) 22 g
(C) 38 g
(D) 44 g
(E) 88 g
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