Q: How many molecules are present in 0.500 mole of $\mathrm{CO_2}$?

$3.01 \times 10^{23}$ molecules

Q: Which of the following is true about Avogadro's number?

It is the number of particles in one mole, $6.02 \times 10^{23}$.

Question 1

Which observation is NOT typically evidence of a chemical change?

Accepted Answer

Melting of ice

Question 2

Which of the following is the correct balanced equation for the reaction of solid iron(III) oxide with hydrogen gas to produce solid iron and liquid water?

Accepted Answer

$\mathrm{Fe_2O_3(s) + 3H_2(g) \rightarrow 2Fe(s) + 3H_2O(l)}$

Question 3

How many molecules are present in 0.500 mole of $\mathrm{CO_2}$?

Accepted Answer

$3.01 	imes 10^{23}$ molecules

Question 4

What is the mass, in grams, of 1.8 $	imes$ $10^{24}$ atoms of sulfur ($\mathrm{S}$)? (Molar mass of S = 32.07 g/mol)

Accepted Answer

$95.9$ g

Question 5

Which of the following is a decomposition reaction?

Accepted Answer

$\mathrm{2HgO(s) \rightarrow 2Hg(l) + O_2(g)}$

Question 6

A glass of water contains 250. g of water. How many moles of water are in the glass? (Molar mass of $\mathrm{H_2O}$ = 18.02 g/mol)

Accepted Answer

$13.9$ moles

Question 7

Which of the following reactions is a combustion reaction?

Accepted Answer

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

Question 8

How many atoms of hydrogen are present in 0.205 moles of $\mathrm{NH_3}$?

Accepted Answer

$3.70 	imes 10^{23}$ atoms

Question 9

Which statement best describes the law of conservation of mass in a chemical reaction?

Accepted Answer

The total mass of reactants equals the total mass of products.

Question 10

What is the molar mass of lithium carbonate ($\mathrm{Li_2CO_3}$)? (Li: 6.941 g/mol, C: 12.01 g/mol, O: 16.00 g/mol)

Accepted Answer

$73.89$ g/mol

Question 11

In the reaction $\mathrm{2Fe(s) + 3S(s) \rightarrow Fe_2S_3(s)}$, how many moles of sulfur are needed to react with 4 moles of iron?

Accepted Answer

$6$ moles

Question 12

Which of the following is a single replacement reaction?

Accepted Answer

$\mathrm{Zn(s) + 2HCl(aq) \rightarrow ZnCl_2(aq) + H_2(g)}$

Question 13

A reaction produces 13.1 g of water ($\mathrm{H_2O}$). How many grams of oxygen ($\mathrm{O_2}$) were consumed? (Molar mass $\mathrm{H_2O}$ = 18.02 g/mol, $\mathrm{O_2}$ = 32.00 g/mol, $\mathrm{2H_2 + O_2 \rightarrow 2H_2O}$)

Accepted Answer

$11.6$ g

Question 14

Which of the following is the limiting reactant when 2.50 g of $\mathrm{N_2}$ reacts with 2.00 g of $\mathrm{H_2}$ to form $\mathrm{NH_3}$? (Molar masses: $\mathrm{N_2}$ = 28.014 g/mol, $\mathrm{H_2}$ = 2.016 g/mol, $\mathrm{NH_3}$ = 17.031 g/mol, $\mathrm{N_2 + 3H_2 \rightarrow 2NH_3}$)

Accepted Answer

$\mathrm{H_2}$

Question 15

Which of the following is true about Avogadro's number?

Accepted Answer

It is the number of particles in one mole, $6.02 	imes 10^{23}$.

Question 16

Which reaction type best describes the following: $\mathrm{AgNO_3(aq) + NaCl(aq) \rightarrow AgCl(s) + NaNO_3(aq)}$?

Accepted Answer

Double replacement

Question 17

Which of the following statements about exothermic reactions is correct?

Accepted Answer

Heat is released and the energy of the products is less than the reactants.

Question 18

How many moles of $\mathrm{NaCl}$ are present in a box containing 737 g of $\mathrm{NaCl}$? (Molar mass $\mathrm{NaCl}$ = 58.44 g/mol)

Accepted Answer

$12.6$ moles

Question 19

Which of the following is the correct mole-to-mole ratio for the reaction $\mathrm{4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)}$?

Accepted Answer

$4$ moles Fe : $3$ moles O$_2$ : $2$ moles Fe$_2$O$_3$

Chapter 7 – Chemical Reactions and Quantities: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards