Q: Which statement best describes Avogadro's number?

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

Q: If $$2.5$$ moles of $$\mathrm{O_2$}$$ are required for a reaction, how many molecules of $$\mathrm{O_2$}$$ does this represent?

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

Question 1

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

Accepted Answer

Iron(III) chloride

Question 2

Which of the following compounds is named using numerical prefixes?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 3

What is the correct formula for dinitrogen pentoxide?

Accepted Answer

$$\mathrm{N_2O_5}$$

Question 4

Which of the following is a double displacement reaction?

Accepted Answer

$$\mathrm{$$AgNO_3$$ + NaCl \rightarrow AgCl + $$NaNO_3$$}$$

Question 5

A student mixes solutions of $$\mathrm{$$BaCl_2$$}$$ and $$\mathrm{Na_2SO_4}. $$What type of reaction occurs and what is the precipitate formed?

Accepted Answer

Double displacement; $$\mathrm{$$BaSO_4$$}$$

Question 6

Which of the following is the correct net ionic equation for the reaction between $$\mathrm{$$AgNO_3$$}$$ and $$\mathrm{NaCl} in $$aqueous solution?

Accepted Answer

$$\mathrm{Ag^+ (aq) + Cl^- (aq) \rightarrow AgCl (s)}$$

Question 7

How many moles are in 18 grams of water ($$\mathrm{H_2O}$$)? ($$\mathrm{H}$$: 1 g/mol, $$\mathrm{O}$$: 16 g/mol)

Accepted Answer

$$1$$ mole

Question 8

Which statement best describes Avogadro's number?

Accepted Answer

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

Question 9

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

Accepted Answer

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

Question 10

Which of the following reactions is an example of a gas evolution reaction?

Accepted Answer

$$\mathrm{H_2SO_4 + Na_2CO_3 \rightarrow Na_2SO_4 + H_2O + CO_2$}$$

Question 11

If $$2.5$$ moles of $$\mathrm{O_2$}$$ are required for a reaction, how many molecules of $$\mathrm{O_2$}$$ does this represent?

Accepted Answer

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

Question 12

Which of the following is the correct balanced equation for the decomposition of $$\mathrm{H_2CO_3}$$?

Accepted Answer

$$\mathrm{H_2CO_3 \rightarrow H_2O + CO_2$}$$

Question 13

A student needs to prepare $$0.5$$ moles of $$\mathrm{NaCl}. $$How many grams of $$\mathrm{NaCl}$$ are required? ($$\mathrm{Na}$$: 23 g/mol, $$\mathrm{Cl}$$: 35.5 g/mol)

Accepted Answer

$$29.25$$ grams

Question 14

Which of the following best describes the concept of enthalpy ($$\Delta H) in $$chemical reactions?

Accepted Answer

It is the heat change at constant pressure.

Question 15

In a reaction, $$4$$ grams of $$\mathrm{H_2$}$$ react with excess $$\mathrm{O_2$} to $$produce water. What is the theoretical yield of water? ($$\mathrm{H_2$}$$: 2 g/mol, $$\mathrm{H_2O}$$: 18 g/mol)

Accepted Answer

$$36$$ grams

Question 16

Which of the following is a correct application of the limiting reactant concept?

Accepted Answer

It determines the maximum amount of product formed in a reaction.

Question 17

A reaction has a theoretical yield of $$50$$ grams, but only $$40$$ grams are obtained. What is the percent yield?

Accepted Answer

$$80\%$$

Question 18

Which of the following is the correct molecular formula for a compound with an empirical formula $$\mathrm{C_2H_5}$$ and a molar mass of $$58 g/$$mol?

Accepted Answer

$$\mathrm{C_4H_{10}}$$

Question 19

Which of the following is a correct molecular (total) equation for the reaction of $$\mathrm{Na_2SO_4}$$ and $$\mathrm{$$BaCl_2$$} in $$water?

Accepted Answer

$$\mathrm{Na_2SO_4 (aq) + $$BaCl_2$$ (aq) \rightarrow $$BaSO_4$$ (s) + 2NaCl (aq)}$$

Introduction to Chemistry: Key Concepts and Study Guide

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