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Gas Stoichiometry — Unit test Answers

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The chemical equation below shows the formation of aluminum oxide (Al2O3) from aluminum (Al) and oxygen (O2).4Al + 3O2 2Al2O3The molar mass of O2 is 32.0 g/mol. What mass, in grams, of O2 must react to form 3.80 mol of Al2O3?

Question illustration
A
60.8 grams
B
81.1 grams
C
122 grams
D
182 grams
2
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The chemical equation below shows the decomposition of ammonium nitrate (NH4NO3).NH4NO3 N2O + 2H2OA chemist who is performing this reaction starts with 160.1 g of NH4NO3. The molar mass of NH4NO3 is 80.03 g/mol; the molar mass of water (H2O) is 18.01 g/mol. What mass, in grams, of H2O is produced?

Question illustration
A
9.01 grams
B
18.01 grams
C
36.03 grams
D
72.06 grams
3

The pictures below show samples of different substances.The mass and volume of each sample differ from the mass and volume of the other samples. Is it possible for each sample to contain 1 mol of each substance?

Question illustration
A
No, because they have different masses.
B
No, because they have different volumes.
C
Yes, if each sample contains 6.02 x 1023 atoms.
D
Yes, if each sample contains 2 amu.
4

What is the relationship between a mole and Avogadro’s number?

A
A mole is the mass of Avogadro’s number of particles of a substance.
B
A mole is the amount of a compound that has Avogadro’s number of carbon-12 atoms in it.
C
A mole contains Avogadro’s number of particles of a substance.
D
A mole is the amount of any substance that has the same mass as Avogadro’s number of carbon-12 atoms.
5

Consider the balanced equation below. What is the mole ratio of PCl3 to PCl5?

Question illustration
A
1:1
B
2:1
C
3:5
D
5:3
6

A tire at 21°C has a pressure of 0.82 atm. Its temperature decreases to –3.5°C. If there is no volume change in the tire, what is the pressure after the temperature change?Use .

Question illustration
A
0.75 atm
B
0.89 atm
C
1.1 atm
D
1.3 atm
7

Shana solves stoichiometry problems using the equation for the synthesis of water.Which interpretation of the balanced equation would cause Shana to make a mistake?

Question illustration
A
Two moles of hydrogen react with one mole of oxygen to form two moles of water.
B
Two grams of hydrogen react with one gram of oxygen to form two grams of water.
C
Two molecules of hydrogen react with one molecule of oxygen to form two molecules of water.
D
Two liters of hydrogen react with one liter of oxygen to form two liters of water.
8

The volume of a gas decreases to half of its original volume, but the gas maintains the same number of moles and temperature. According to the ideal gas law, what will most likely happen to the pressure?

A
It will double.
B
It will decrease.
C
It will increase slightly.
D
It will remain the same.
9

Which statement best explains the purpose of using a mole in the measurement of matter?

A
It is commonly used as another unit of mass.
B
It allows chemists to deal with a large number of atoms.
C
It is used only for studying the properties of gases.
D
It explains that substances with the same moles have the same mass.
10

Consider the reaction.How many grams of carbon should be burned in an excess of oxygen at STP to obtain 2.21 L of carbon dioxide?

Question illustration
A
1.18 g
B
2.21 g
C
4.12 g
D
4.34 g
11

A chemical equation can be used to solve stoichiometry problems provided that it

A
indicates only the forward reaction and not the reverse.
B
indicates that reactants are in the gas phase and are not solids or liquids.
C
includes the coefficients that are needed for balancing the equation.
D
includes the state of matter after each substance.
12

Consider the substances below.• 1 mol of beryllium• 1 mol of salt• 1 mol of water• 1 mol of hydrogenWhich statement is true about these substances?

A
They have exactly the same mass.
B
They have different numbers of particles.
C
They have the same number of atoms.
D
They have different masses.
13

What is the volume of 0.200 mol of an ideal gas at 200. kPa and 400. K?Use and .

Question illustration
A
0.83 L
B
3.33 L
C
5.60 L
D
20.8 L
14

Consider the reaction.Which statement is true at STP? (The atomic mass of Mg is 24.31 u.)

Question illustration
A
3.0 g of Mg produce 3.0 L of H2 gas.
B
3.0 g of Mg produce 22.4 L of H2 gas.
C
24.31 g of Mg produce (3 22.4) L of H2 gas.
Option C
D
(3 24.31) g of Mg produce (3 22.4) L of H2 gas.
Option D
15

The molar mass of water (H2O) is 18.0 g/mol. A sample of water has a mass of 18.0 g. How many moles of water are contained in this sample?

A
1.00 mole
B
18.0 moles
C
36.0 moles
D
324 moles

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