Q: Which of the following best describes the mole in chemistry?

A unit that represents $$6.022 \times 10$$^{23}$$ particles of a substance.

Q: How many atoms are present in 2.00 moles of magnesium?

$$1.20 \times 10$$^{24}$$ atoms

Q: A pure copper ring has a mass of 4.00 grams. How many copper atoms does it contain? (Molar mass of Cu = 63.55 g/mol)

$$3.79 \times 10$$^{22}$$ atoms

Q: A chemist has 0.250 mol of silver. How many silver atoms does she have?

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

Q: If you have 0.100 mol of gold, how many gold atoms do you have?

$$6.02 \times 10$$^{22}$$ atoms

Q: Which of the following is the correct conversion factor to use when converting from moles to atoms?

$$6.022 \times 10$$^{23}$$ atoms/1 mol

Q: A ring is made from 2.5 grams of pure silver (molar mass = 107.87 g/mol). How many silver atoms are in the ring?

$$1.40 \times 10$$^{22}$$ atoms

Question 1

Which of the following best describes the mole in chemistry?

Accepted Answer

A unit that represents $$6.022 	imes 10$$^{23}$$ particles of a substance.

Question 2

How many atoms are present in 2.00 moles of magnesium?

Accepted Answer

$$1.20 	imes 10$$^{24}$$ atoms

Question 3

A pure copper ring has a mass of 4.00 grams. How many copper atoms does it contain? (Molar mass of Cu = 63.55 g/mol)

Accepted Answer

$$3.79 	imes 10$$^{22}$$ atoms

Question 4

Which of the following contains the greatest number of atoms?
A. A 5-gram pure gold ring
B. A 2.5-gram pure silver necklace
C. A 10-gram pure aluminum sheet
D. A 3-gram pure magnesium foil

Accepted Answer

A 10-gram pure aluminum sheet

Question 5

Calculate the number of moles in a 35.8-gram pure copper sheet. (Molar mass of Cu = 63.55 g/mol)

Accepted Answer

$$0.564$$ mol

Question 6

What is the mass of 0.473 mol of titanium? (Molar mass of Ti = 47.87 g/mol)

Accepted Answer

$$22.6 g$$

Question 7

Which equation correctly relates the number of moles ($$n$$), mass ($$m$$), and molar mass ($$M) of a $$substance?

Accepted Answer

$$n = \frac{m}{M}$$

Question 8

A chemist has 0.250 mol of silver. How many silver atoms does she have?

Accepted Answer

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

Question 9

Which of the following statements about the mole is FALSE?

Accepted Answer

One mole of hydrogen atoms weighs 1 gram.

Question 10

A sample contains $$3.01 	imes 10$$^{23}$$ atoms of aluminum. What is the mass of the sample? (Molar mass of Al = 26.98 g/mol)

Accepted Answer

$$13.5 g$$

Question 11

Which of the following best explains why chemists use the mole concept?

Accepted Answer

To count large numbers of atoms or molecules using measurable masses.

Question 12

If you have 0.100 mol of gold, how many gold atoms do you have?

Accepted Answer

$$6.02 	imes 10$$^{22}$$ atoms

Question 13

A student weighs out 12.0 grams of carbon (molar mass = 12.01 g/mol). How many moles of carbon does she have?

Accepted Answer

$$1.00$$ mol

Question 14

Which of the following is the correct conversion factor to use when converting from moles to atoms?

Accepted Answer

$$6.022 	imes 10$$^{23}$$ atoms/1 mol

Question 15

A ring is made from 2.5 grams of pure silver (molar mass = 107.87 g/mol). How many silver atoms are in the ring?

Accepted Answer

$$1.40 	imes 10$$^{22}$$ atoms

Question 16

Which of the following is NOT a correct step in converting from grams of a substance to number of atoms?

Accepted Answer

Multiply the mass by Avogadro's number directly.

Atoms, Elements, and the Mole: Quantifying Matter in Chemistry

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