Q: What is the molar mass of CO$$_2$$? (Atomic masses: C = 12.01 g/mol, O = 16.00 g/mol)

$$12.01 + 2 \times 16.00 = 44.01 g/$$mol

Q: How many atoms are present in 2.5 moles of carbon atoms? (Avogadro’s number $$= 6.022 \times 10$$^{23}$$ atoms/mol)

$$2.5 \times 6.022 \times 10$$^{23}$$ = 1.506 \times 10$$^{24}$$ atoms

Q: What is the formula weight of H$$_2O$$? (Atomic masses: H = 1.01 amu, O = 16.00 amu)

$$2 \times 1.01 + 16.00 = 18.02$$ amu

Q: Which statement about the mole is correct?

A mole is a counting unit equal to $$6.022 \times 10$$^{23}$$ particles

Q: Which of the following statements about Avogadro’s number is TRUE?

It is the number of particles in one mole, $$6.022 \times 10$$^{23}$$

Q: A sample contains $$3.01 \times 10$$^{23}$$ molecules of CO_2$. How many moles of CO_2$ are present?

$$\frac{3.01 \times 10$$^{23}$$}{6.022 \times 10$$^{23}$$} = 0.5$$ moles

Q: What is the molar mass of P$$_2O$_5$$? (Atomic masses: P = 30.97 g/mol, O = 16.00 g/mol)

$$2 \times 30.97 + 5 \times 16.00 = 141.94 g/$$mol

Question 1

Which of the following is the correct name for the compound PBr$$_3$$?

Accepted Answer

Phosphorus tribromide

Question 2

What is the correct formula for dinitrogen tetroxide?

Accepted Answer

N$$_2O$_4$$

Question 3

Which prefix is used to indicate '5' atoms in a covalent compound?

Accepted Answer

penta-

Question 4

A compound is formed between two nonmetals. Which naming convention should be used?

Accepted Answer

Greek prefixes to indicate the number of atoms

Question 5

What is the molar mass of CO$$_2$$? (Atomic masses: C = 12.01 g/mol, O = 16.00 g/mol)

Accepted Answer

$$12.01 + 2 	imes 16.00 = 44.01 g/$$mol

Question 6

How many atoms are present in 2.5 moles of carbon atoms? (Avogadro’s number $$= 6.022 	imes 10$$^{23}$$ atoms/mol)

Accepted Answer

$$2.5 	imes 6.022 	imes 10$$^{23}$$ = 1.506 	imes 10$$^{24}$$ atoms

Question 7

Which of the following compounds is named correctly?

Accepted Answer

Sulfur dioxide for SO$$_2$$

Question 8

What is the formula weight of H$$_2O$$? (Atomic masses: H = 1.01 amu, O = 16.00 amu)

Accepted Answer

$$2 	imes 1.01 + 16.00 = 18.02$$ amu

Question 9

Which statement about the mole is correct?

Accepted Answer

A mole is a counting unit equal to $$6.022 	imes 10$$^{23}$$ particles

Question 10

If you have 18.02 grams of water (H$$_2O$$), how many moles do you have? (Molar mass of H$$_2O = 18.02 g/$$mol)

Accepted Answer

$$\frac{18.02}{18.02} = 1$$ mole

Question 11

Which of the following is NOT a correct step in naming a binary covalent compound?

Accepted Answer

Use Roman numerals to indicate the charge of the first element

Question 12

What is the correct name for NF$$_3$$?

Accepted Answer

Nitrogen trifluoride

Question 13

Which of the following statements about Avogadro’s number is TRUE?

Accepted Answer

It is the number of particles in one mole, $$6.022 	imes 10$$^{23}$$

Question 14

A sample contains $$3.01 	imes 10$$^{23}$$ molecules of CO_2$. How many moles of CO_2$ are present?

Accepted Answer

$$\frac{3.01 	imes 10$$^{23}$$}{6.022 	imes 10$$^{23}$$} = 0.5$$ moles

Question 15

Which of the following is the correct name for SCl$$_2$$?

Accepted Answer

Sulfur dichloride

Question 16

What is the molar mass of P$$_2O$_5$$? (Atomic masses: P = 30.97 g/mol, O = 16.00 g/mol)

Accepted Answer

$$2 	imes 30.97 + 5 	imes 16.00 = 141.94 g/$$mol

Question 17

Which of the following is a correct real-world analogy for the mole?

Accepted Answer

A mole is like a dozen, but for atoms

Question 18

Which of the following compounds is NOT named using Greek prefixes?

Accepted Answer

NaCl

Question 19

If you have 0.75 moles of H$$_2O$$, how many molecules do you have? (Avogadro’s number $$= 6.022 	imes 10$$^{23}$$ molecules/mol)

Accepted Answer

$$0.75 	imes 6.022 	imes 10$$^{23}$$ = 4.52 	imes 10$$^{23}$$ molecules

Chapter 3: Naming Covalent Compounds and Counting Atoms in Chemistry

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