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41
STOICHIOMETRY
Multiple Choice Questions
2. Ammonia forms when hydrogen gas reacts with nitrogen gas. If equal
number of moles of nitrogen and hydrogen are combined, the maximum
number of moles of ammonia that could be formed will be equal to
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A) the number of moles of hydrogen.
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B) the number of moles ofhitrogen.
C) twice the number of moles of hydrogen
D) twice the number of moles of nitrogen
Entwo thirds the number of moles of hydrogen
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2. IfCflwO undergoes complete combustion, what is the sum of the
coefficients when the equation is completed and balanced using
smallest whole numbers?
A) 8
12=
3. What are the products when lithium carbonate is heated?
A) LiOH+CO2
10\j^0 + C02
C) LiO + CO2
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D) LiC + 02
E) LiO -f- CO
4. Beginning with 48 moles ofH2, how many moles ofCu(NHJ£H2(aq)
can be obtained if the synthesis ofCuCNHJfl^aq) is carried out
through the following sequential reactions? Assume that a 50%
yield of produces) is(are) obtained in each reaction.
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1. 3H2(g) + N2(g) --*- 2NH3(g)
2. 4 NH3(g) + CuSOJaq) ~*
3. Cu(NHSO4 + 2NaCl ~*~ Cu(NHJ4O2(acj)
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5 mat mass of water can be obtained from 4.0 g ofH2 and 16 g ofO2?
2H2(g) + 02(g) - *- 2 HP
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6. The empirical formula ofpyrogallol is C2H2O and its molar mass is
126. Its molecular formula is
\ Cfl20
B) CHp2
0
3 -
Cflp3
E) C2H606
, is the maximum amount of water that can be prepared from the !|
ion of 20.0 g of HBr with 20.0 g of Ca(OH)2?
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~B) (20/74X2/2X18) g
C) (20/81X2/1X18) g
D) (20/74X2/1X18) g
E) (20/74X1/2X18) g
8. How many moles of of ozone, O3/ could be formed from 96.0 g of ..-.iJJP
oxygen gas, O2?
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A) 0.500 mol
%
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\. Oz -"^l °3
B) 1.00 mol
STOICHIOMETRY
43
12.00 mol
D) 3.00 mol
E) 1/16 mol
9. The percentage of oxygen in CHrO, is:
^)16/140)(100)
B) (32/140)(100)
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C) (16/124)(100)
D) (140/32X100)
E) (32/124)(100)
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10. A compound contains 48% O, 40.0% Ca, and the remainder is C. ^ *~ *& ~ %& °/Q
What is its empirical formula?
A) 0,CA,
B) OpX
j
__Z^~--~
5 M<"
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"ijTT"
~ " '" '
'12
C
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D) O3CCa2
E) O,CCa
Free Response Question
1. Combustion of 8.652 grams of a compound containing C, H, O, and
N yields 11.088 g of CO, 3.780 grams cfH,O and 3.864 grams of
NO,.
a. How many moles ofC, H, and N are contained in the sample?
b. How many grams of oxygen are contained in the sample?
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c. What is the simplest formula of the compound?
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.
d. If the molar mass of the compound lies between 200 and 300, what is
its molecular formula?
e.
Write and balance a chemical equation for the combustion of the compound.
Additional Practice in Chemistry the Central Science
For more practice answering questions in preparation for the Advanced
Placement examination try these problems in Chapter 3 of Chemistry
the Central Science:
Additional Exercises: 3.81, 3.84, 3.86, 3.88, 3.89, 3.90, 3.91, 3.96, 3.98,
3.99, 3.100.
Integrate Exercises: 3.103, 3.104,3.105, 3.107.
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