$$1.51 \times 10$$^{24}$$ molecules

$$9.61 \times 10$$^{24}$$ atoms

$$\frac{\text{mass of element in compound}}{\text{mass of compound}} \times 100\%$$

$$\frac{1\ \text{mol}}{\text{molar mass in g}}$$

$$3.61 \times 10$$^{24}$$ atoms

Question 1

Which of the following best describes a mole in chemistry?

Accepted Answer

A unit that represents Avogadro’s number of particles, specifically 6.022 	imes $$10^{23}$$ items.

Question 2

How many molecules are present in 2.50 moles of sucrose ($$C_{12}H$$_{22}$$O_{11}$)?

Accepted Answer

$$1.51 	imes 10$$^{24}$$ molecules

Question 3

What is the molar mass of sodium bicarbonate ($$NaHCO_3$$)?

Accepted Answer

$$84.01\ \mathrm{g/mol}$$

Question 4

If you have 26 grams of carbon, how many moles of carbon do you have? ($$M_{C} = 12.01\ \mathrm{g/mol})$$

Accepted Answer

$$2.2$$ moles

Question 5

How many oxygen atoms are present in 5.32 moles of calcium carbonate ($$CaCO_3$$)?

Accepted Answer

$$9.61 	imes 10$$^{24}$$ atoms

Question 6

Which of the following statements about empirical and molecular formulas is correct?

Accepted Answer

The empirical formula shows the simplest whole-number ratio of elements in a compound.

Question 7

What is the empirical formula for glucose ($$C_6H_{12}O_6$)?

Accepted Answer

$$CH_2O$$

Question 8

A sample contains $$1.204 	imes 10$$^{24}$$ molecules of water. How many moles of water are present?

Accepted Answer

$$2.00$$ moles

Question 9

Which of the following is the correct formula to calculate the mass percent of an element in a compound?

Accepted Answer

$$\frac{	ext{mass of element in compound}}{	ext{mass of compound}} 	imes 100\%$$

Question 10

Which of the following best explains why the mole is a useful unit in chemistry?

Accepted Answer

It allows chemists to count atoms and molecules by weighing macroscopic amounts of material.

Question 11

What is the molar mass of $$C_{12}H$$_{22}$$O_{11}$ (sucrose)?

Accepted Answer

$$342.34\ \mathrm{g/mol}$$

Question 12

A chemist has 18.02 grams of water ($$H_2O). $$How many moles of water does she have?

Accepted Answer

$$1.00$$ mole

Question 13

Which of the following compounds has the same empirical formula as glucose ($$C_6H_{12}O_6$)?

Accepted Answer

Glycolaldehyde ($$C_2H_4O_2)$$

Question 14

How many sodium ions are present in 1 mole of sodium chloride ($$NaCl$$)?

Accepted Answer

$$6.022 	imes 10$$^{23}$$

Question 15

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

Accepted Answer

$$\frac{1\ 	ext{mol}}{	ext{molar mass in g}}$$

Question 16

A sample of $$CaCO_3$$ contains $$1.00 	imes 10$$^{24}$$ formula units. How many moles of $$CaCO_3$$ are present?

Accepted Answer

$$0.166$$ moles

Question 17

Which of the following best describes the relationship between empirical and molecular formulas?

Accepted Answer

The molecular formula is always a whole-number multiple of the empirical formula.

Question 18

If you have 3.00 moles of $$O_2$$ molecules, how many oxygen atoms do you have?

Accepted Answer

$$3.61 	imes 10$$^{24}$$ atoms

The Mole, Avogadro’s Number, Molar Mass, and Chemical Formulas

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