Q: Which of the following best defines a mole in chemistry?

The amount of substance containing $$6.022 \times 10$$^{23}$$ entities (Avogadro's number).

Question 1

Which of the following best defines a mole in chemistry?

Accepted Answer

The amount of substance containing $$6.022 	imes 10$$^{23}$$ entities (Avogadro's number).

Question 2

What is the molar mass of $$CO_2$$?

Accepted Answer

$$44.01 \ \mathrm{g/mol}$$

Question 3

How many moles are in $$48.0 \ \mathrm{g} of$$ $$O_2$$? (Molar mass $$O_2 = 32.0$$ \ \mathrm{g/mol}$$)

Accepted Answer

$$1.5$$ moles

Question 4

A sample contains $$1.5$$ moles of $$O_2. $$How many grams does this represent? (Molar mass $$O_2 = 32.0$$ \ \mathrm{g/mol}$$)

Accepted Answer

$$48.0 \ \mathrm{g}$$

Question 5

Which compound has the highest percent by mass of sodium?

Accepted Answer

$$NaCl$$

Question 6

What is the empirical formula of a compound that is $$69.9\%$$ iron and $$30.1\%$$ oxygen by mass? (Molar masses: Fe = $$55.8 \ \mathrm{g/mol}$$, O = $$16.0 \ \mathrm{g/mol})$$

Accepted Answer

$$Fe_2O_3$$

Question 7

Balance the following equation: $$NH_3$$ + $$O_2$$ \rightarrow NO + H_2O$$

Accepted Answer

$$4NH_3 + 5O_2 \rightarrow 4NO + 6H_2O$$

Question 8

How many grams of $$CO_2$$ are formed when $$24.0 \ \mathrm{g} of$$ $$CH_4$$ reacts with excess oxygen? ($$CH_4 + 2O_2$$ \rightarrow $$CO_2 + 2H_2O$, Molar mass CH_4$ = 16.0 \ \mathrm{g/mol}$$, $$CO_2 = 44.0$$ \ \mathrm{g/mol}$$)

Accepted Answer

$$66.0 \ \mathrm{g}$$

Question 9

Which of the following statements about limiting reagents is correct?

Accepted Answer

The limiting reagent is the reactant that determines the maximum amount of product formed.

Question 10

A cube has a side of $$5.0 \ \mathrm{cm}. If it $$has a mass of $$500 \ \mathrm{g}$$, what is its density?

Accepted Answer

$$4.0 \ \mathrm{g/cm^3$}$$

Question 11

What is the percent yield if a reaction produces $$13 \ \mathrm{g} of $$benzene and the theoretical yield is $$15 \ \mathrm{g}$$?

Accepted Answer

$$86.7\%$$

Question 12

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

Accepted Answer

Empirical formulas show the simplest whole-number ratio of atoms, while molecular formulas show the actual number of atoms in a molecule.

Question 13

If $$0.5$$ moles of $$NaCl is$$ $$29.25 \ \mathrm{g}$$, what is the mass of $$1.0$$ mole of $$NaCl$$?

Accepted Answer

$$58.5 \ \mathrm{g}$$

Question 14

What is the percent composition of hydrogen in $$H_2O$$?

Accepted Answer

$$11.2\%$$

Question 15

A compound contains $$40.0\% C$$, $$6.7\% H$$, and $$53.3\% O by $$mass. What is its empirical formula?

Accepted Answer

$$CH_2O$$

Question 16

Which of the following is NOT a correct step in balancing a chemical equation?

Accepted Answer

Change the subscripts of compounds to balance the equation.

Question 17

How many moles of $$H_2O$$ are produced when $$5$$ moles of $$O_2$$ are reacted with excess $$H_2$$? ($$2H_2 + O_2$ \rightarrow 2H_2O)$$

Accepted Answer

$$10$$ moles

Question 18

Which of the following is the correct formula for a compound whose composition is $$30.4\% N $$and $$69.6\% O by $$mass?

Accepted Answer

$$NO_2$$

Question 19

If $$500 \ \mathrm{g} of $$water ($$\rho = 1.0 \ \mathrm{g/mL}) $$fills up a water bottle, what is the mass of pure orange juice ($$\rho = 1.25 \ \mathrm{g/mL}) to $$fill the same bottle?

Accepted Answer

$$625 \ \mathrm{g}$$

Question 20

Which of the following is true about actual yield in a chemical reaction?

Accepted Answer

Actual yield is the amount of product actually obtained from a reaction.

Moles, Molar Mass, Percent Composition, Empirical & Molecular Formulas, Balancing Equations, Limiting Reagents, Density, and Percent Yield

Study Guide - Practice Questions

Study Guide - Flashcards