HOMEWORK PACK 4
STOICHIOMETRY
1.
Find the mass of each of the following:
(a)
0.50 mole of NaOH
(b)
4.5 moles of CaCO3
(c)
0.25 mole of Ba(NO3)2
(d)
3.00 moles of sodium oxide
2.
How many moles are contained in each of the following?
(a) 60. grams of NaOH
(b) 75 grams of CaCO3
(c) 26.1 grams of Ba(N03)2
(d) 310 grams of sodium oxide
3.
If the mass of 0.60 mole of a certain substance is 72 grams, what is the molar
mass of the substance?
4.
Find the empirical formula of the following compounds.
(a) H202
(b) C7H12
(c) C6H5
5.
Find the empirical formula of the following compounds that contain:
(a) 75 percent C, 25 percent H
(b) 40 percent Ca, 12 percent C, 48 percent 0
(c) 2.5 percent H, 57.5 percent sodium, 40 percent 0
(d) 40.0 percent carbon, 6.7 percent hydrogen, and 53.3 percent oxygen
(e) 66.0 percent calcium and 34.0 percent phosphorus
(f) 8.3 percent aluminum, 32.7 percent chlorine, and 59.0 percent oxygen
6.
Find the empirical formula for the following compounds that contain:
(a) 1.8 grams Ca and 3.2 grams Cl
(b) 8.8 grams Cs and 2.35 grams Cl
(c) 233.7 grams Al and 416 grams S
(d) 10.26 grams Ni, 4.90 grams N, and 16.8 grams 0
7.
The empirical formula of benzene is CH and its molecular mass is 78 grams. What
is benzene’s molecular formula?
8.
A hydrocarbon contains 85.7 percent carbon and 14.3 percent hydrogen by mass.
Its molecular mass is 70 g/mole. Find its molecular formula.
9.
The butane gas used in lighters has a molar mass of 58 g/mole. Its empirical
formula is C2H5. Find the molecular formula of butane.
10.
The molecular mass of aspirin is 180 g/mole. Its percent composition is 60.0
percent carbon, 4.48 percent hydrogen, and 35.5 percent oxygen. What is aspirin’s
molecular formula?
11.
Base your answers on the balanced equation
N2 + 3H2  2NH3
(a) How many moles of hydrogen are needed to produce 6.0 moles of ammonia?
(b) How many moles of nitrogen are required to react with 0.60 mole of hydrogen?
(c) How many moles of ammonia are formed from 0.5O mole of nitrogen and excess
hydrogen?
12.
Base your answers on this balanced equation:
2 Pb(CH3)4 + 15 O2  2 PbO + 8 CO2 + 12 H20
(a) How many moles of O2 are needed to burn 4.6 moles of Pb(CH3)4?
(b) How many moles of CO2 are produced by burning 5 moles of Pb(CH3)4?
(c) How many moles of water will be produced by reacting 7.5 moles of O2?
13.
Change each quantity to moles.
(a) 36 g of water
(b) 6.0 g of NaOH
(c) 40 g of CaCO3
(d) 44.8 L of CO2 at STP
(e) 11.2 L of He at STP
(f) 56 of O2 at STP
14.
Find the mass in grams of each of the following.
(a) 1.5 moles of H2O
(d) 44.8 L of H2 at STP
(b) 0.30 mole of N2
(e) 56 L of Ne at STP
(c) 0.40 mole of NO2
(f) 5.6L of O2 at STP
15.
Find the volume in liters at STP for each of the following ideal gases.
(a) 3.0 moles of Ar
(d) 16 g of He
(b) 0.40 mole of CO2
(e) 16 g of 02
(c) 1.5 mole of Cl2
(f) 4.4g of N2O
16.
Find the density at STP of the following gases:
(a) CO
(b) O2
(c) Ar
(d) NH3
17.
What is the molecular mass of a gas that has a density at STP of 1.98 grams/liter?
18.
At STP, 4.00 liters of a certain gas has a mass of 11.4 grams. What is the
molecular mass of this gas?
19.
C2H5OH+ 3O2  2CO2+ 3H20
In the combustion of ethanol, shown above, how many grams of carbon dioxide are
produced when 23 grams of ethanol are burned completely?
20.
In the reaction,
Na20 + H202 NaOH
how many moles of sodium oxide are needed to prepare 20 grams of NaOH?
21.
In the reaction,
22.
Consider the reaction
C3H8(g) + 5 O2(g)  3 CO2(g) + 4 H2O(g)
How many liters of oxygen are required to produce 45 liters of carbon dioxide?
23.
In the reaction,
24.
In the reaction,
25.
Oxygen is produced by the decomposition of hydrogen peroxide, through the
reaction:
2H202  2H2O + O2
Starting with 34 grams of H2O2, a student was able to collect 12 grams of 02.
What was the percent yield?
N2+3H2  2NH3.
how many grams of H2 are needed to produce 0.50 mole of NH3?
N2(g) + 3 H2(g)  2 NH3(g)
how many liters of hydrogen are needed to react completely with 30 liters of
nitrogen?
S8(s) + 12 02(g)  8 SO3(g)
(a) How many liters of oxygen gas are needed to produce 24 liters of SO3?
(b) How many moles of S8 must be burned to produce 89.6 liters of SO3 at STP?
(c) Why CAN’T the method used in part (a) of this problem be used to find the
volume of S8 required to produce 24 liters of SO3 at STP?