Q: How many molecules are present in $$0.250$$ mole of water ($$H_2O$$)?

$$1.51 \times 10$$^{23}$$ molecules

Q: Which conversion factor would you use to convert from moles of $$CO_2 to $$molecules of $$CO_2$$?

$$\frac{6.02 \times 10$$^{23}$$\text{ molecules } CO_2$}{1\text{ mole } CO_2$}$$

Q: How many atoms of oxygen are in $$0.150$$ mole of aspirin ($$C_9H_8O_4$$)?

$$3.61 \times 10$$^{23}$$ atoms

Q: Which of the following is NOT a correct use of a mole-mole factor from a balanced equation?

$$\frac{1\text{ mole } Fe_2O_3}{4\text{ moles } Fe} in$$ $$4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)$$

Q: Which of the following is a correct equality for the molar mass of methane ($$CH_4$$)?

$$1\text{ mole } CH_4$ = 16.05\text{ g } CH_4$

Q: Which of the following is a correct conversion factor for converting grams to moles?

$$\frac{1\text{ mole}}{\text{molar mass in grams}}$$

Question 1

Which of the following best describes Avogadro's number?

Accepted Answer

The number of particles in 1 mole of a substance, equal to $$6.02 	imes 10$$^{23}$$.

Question 2

A sample contains $$1.8 	imes 10$$^{24}$$ atoms of sulfur. How many moles of sulfur are present?

Accepted Answer

$$3.0$$ moles

Question 3

How many molecules are present in $$0.250$$ mole of water ($$H_2O$$)?

Accepted Answer

$$1.51 	imes 10$$^{23}$$ molecules

Question 4

Which conversion factor would you use to convert from moles of $$CO_2 to $$molecules of $$CO_2$$?

Accepted Answer

$$\frac{6.02 	imes 10$$^{23}$$	ext{ molecules } CO_2$}{1	ext{ mole } CO_2$}$$

Question 5

A box contains $$737$$ grams of table salt ($$NaCl). $$How many moles of $$NaCl$$ are in the box? (Molar mass of $$NaCl = 58.44 g/$$mol)

Accepted Answer

$$12.6$$ moles

Question 6

How many atoms of oxygen are in $$0.150$$ mole of aspirin ($$C_9H_8O_4$$)?

Accepted Answer

$$3.61 	imes 10$$^{23}$$ atoms

Question 7

What is the molar mass of lithium carbonate ($$Li_2CO_3$$)? (Atomic masses: Li = $$6.94 g/$$mol, C = $$12.01 g/$$mol, O = $$16.00 g/$$mol)

Accepted Answer

$$73.89 g/$$mol

Question 8

A sample of water has a mass of $$59.8$$ grams. How many moles of water are present? (Molar mass of $$H_2O = 18.02 g/$$mol)

Accepted Answer

$$3.32$$ moles

Question 9

In the reaction $$4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)$$, how many moles of $$Fe$$ are needed to react with $$12.0$$ moles of $$O_2$$?

Accepted Answer

$$16.0$$ moles

Question 10

Which statement best describes the law of conservation of mass in a chemical reaction?

Accepted Answer

The total mass of reactants equals the total mass of products.

Question 11

How many grams of $$O_2$$ are needed to produce $$45.8$$ grams of $$Fe_2O_3 in $$the reaction $$4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)$$? (Molar mass: $$Fe_2O_3 = 159.7 g/$$mol, $$O_2 = 32.00$ g/mol)

Accepted Answer

$$13.7 g$$

Question 12

In the reaction $$2H_2(g) + O_2$(g) \rightarrow 2H_2O(g)$$, how many grams of $$O_2$$ are required to produce $$13.1$$ grams of water? (Molar mass: $$H_2O = 18.02 g/$$mol, $$O_2 = 32.00$ g/mol)

Accepted Answer

$$11.6 g$$

Question 13

Which of the following is NOT a correct use of a mole-mole factor from a balanced equation?

Accepted Answer

$$\frac{1	ext{ mole } Fe_2O_3}{4	ext{ moles } Fe} in$$ $$4Fe(s) + 3O_2(g) ightarrow 2Fe_2O_3(s)$$

Question 14

What is the molar mass of $$C_2H_6O ($$ethanol)? (Atomic masses: C = $$12.01 g/$$mol, H = $$1.01 g/$$mol, O = $$16.00 g/$$mol)

Accepted Answer

$$46.08 g/$$mol

Question 15

A compound has the formula $$C_9H_8O_4. $$How many moles of hydrogen are present in $$2.0$$ moles of the compound?

Accepted Answer

$$16$$ moles

Question 16

Which of the following is a correct equality for the molar mass of methane ($$CH_4$$)?

Accepted Answer

$$1	ext{ mole } CH_4$ = 16.05	ext{ g } CH_4$

Question 17

If you have $$2.0$$ moles of aluminum, how many atoms of aluminum do you have?

Accepted Answer

$$1.2 	imes 10$$^{24}$$ atoms

Question 18

Which of the following is a correct conversion factor for converting grams to moles?

Accepted Answer

$$\frac{1	ext{ mole}}{	ext{molar mass in grams}}$$

The Mole, Avogadro's Number, and Calculating Particles in Chemistry

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