Question 1

Which of the following statements best describes the difference between an empirical formula and a molecular formula?

Accepted Answer

The empirical formula shows the simplest whole-number ratio of atoms in a compound, while the molecular formula shows the actual number of atoms of each element in a molecule.

Question 2

A compound has an empirical formula of $$\mathrm{CH_2O}$$ and a molar mass of $$180\ \mathrm{g/mol}. $$What is its molecular formula?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$}$$

Question 3

Which of the following is the correct name for the compound $$\mathrm{$$FeCl_3$$}$$?

Accepted Answer

Iron(III) chloride

Question 4

What is the empirical formula for a compound containing 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 5

Which of the following is the correct name for $$\mathrm{Na_2SO_4}$$?

Accepted Answer

Sodium sulfate

Question 6

A sample of chlorine contains two isotopes: $$^{35}\mathrm{Cl} (75.8$$% abundance, mass = 34.969 amu) and $$^{37}\mathrm{Cl} (24.2$$% abundance, mass = 36.966 amu). What is the average atomic mass of chlorine?

Accepted Answer

$$35.45\ \mathrm{amu}$$

Question 7

Which of the following is the correct balanced equation for the combustion of methane ($$\mathrm{CH_4$}) in $$oxygen?

Accepted Answer

$$\mathrm{CH_4$ + 2O_2 \rightarrow CO_2$ + 2H_2O}$$

Question 8

Which of the following compounds is named correctly?

Accepted Answer

$$\mathrm{SO_3$}$$: Sulfur trioxide

Question 9

A chemical reaction is represented as $$\mathrm{2Al + 3Cl_2 \rightarrow 2AlCl_3}. If $$you start with 4 moles of $$\mathrm{Al}$$ and excess $$\mathrm{Cl_2$}$$, how many moles of $$\mathrm{$$AlCl_3$$}$$ will be produced?

Accepted Answer

4 moles

Question 10

Which of the following is the correct empirical formula for glucose ($$\mathrm{C_6H_{12}O_6$}$$)?

Accepted Answer

$$\mathrm{CH_2O}$$

Question 11

Which of the following is the correct name for $$\mathrm{P_2O_5}$$?

Accepted Answer

Diphosphorus pentoxide

Question 12

A compound contains 30.4% nitrogen and 69.6% oxygen by mass. What is its empirical formula?

Accepted Answer

$$\mathrm{NO_2$}$$

Question 13

Which of the following is the correct balanced equation for the reaction between sodium and water?

Accepted Answer

$$\mathrm{2Na + 2H_2O \rightarrow 2NaOH + H_2$}$$

Question 14

Which of the following is the correct name for $$\mathrm{$$CaCl_2$$}$$?

Accepted Answer

Calcium chloride

Question 15

A sample contains 92.5% carbon and 7.5% hydrogen by mass. What is the empirical formula?

Accepted Answer

$$\mathrm{C_2H_2}$$

Question 16

Which of the following is the correct name for $$\mathrm{N_2O_4}$$?

Accepted Answer

Dinitrogen tetroxide

Question 17

Which of the following is the correct balanced equation for the decomposition of water?

Accepted Answer

$$\mathrm{2H_2O \rightarrow 2H_2 + O_2$}$$

Question 18

Which of the following is the correct name for $$\mathrm{$$KNO_3$$}$$?

Accepted Answer

Potassium nitrate

Question 19

A compound has a molecular formula of $$\mathrm{C_4H_{10}}. $$What is its empirical formula?

Accepted Answer

$$\mathrm{C_2H_5}$$

Question 20

Which of the following is the correct balanced equation for the reaction of hydrogen and oxygen to form water?

Accepted Answer

$$\mathrm{2H_2 + O_2$ \rightarrow 2H_2O}$$

Study Notes: Molecules, Compounds, and Chemical Quantities

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