Q: Given the reaction $$2 \text{H}_2(g) + \text{O}_2(g) \rightarrow 2 \text{H}_2\text{O}(l)$$, how many grams of water are produced from 4.00 g of hydrogen gas?

$$\text{Molar mass of H}_2 = 2.02\ \text{g/mol}$$; $$\text{Molar mass of H}_2\text{O} = 18.02\ \text{g/mol}$$ $$4.00\ \text{g H}_2 \times \frac{1\ \text{mol H}_2}{2.02\ \text{g H}_2} \times \frac{2\ \text{mol H}_2\text{O}}{2\ \text{mol H}_2} \times \frac{18.02\ \text{g H}_2\text{O}}{1\ \text{mol H}_2\text{O}} = 35.7\ \text{g H}_2\text{O}$$

Q: Which of the following is a decomposition reaction?

$$2\text{KClO}_3(s) \rightarrow 2\text{KCl}(s) + 3\text{O}_2(g)$$

Q: What is the net ionic equation for the reaction between aqueous solutions of NaCl and AgNO$$_3$$?

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

Q: Which of the following is the correct balanced equation for the combustion of propane ($$\text{C}_3\text{H}_8$$)?

$$\text{C}_3\text{H}_8 + 5\text{O}_2 \rightarrow 3\text{CO}_2 + 4\text{H}_2\text{O}$$

Q: A sample contains 61.31% C, 5.14% H, 10.21% N, and 23.33% O by mass. What is the empirical formula?

$$\text{C}_7\text{H}_7\text{NO}_2$$

Q: What is the theoretical yield of CO$$_2 (in $$grams) when 10.0 g of C$$_6H$_{12}O$_6$$ reacts completely with excess O$$_2$$? ($$\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O}$$; $$\text{Molar mass of C}_6\text{H}_{12}\text{O}_6 = 180\ \text{g/mol}$$; $$\text{Molar mass of CO}_2 = 44\ \text{g/mol})$$

$$10.0\ \text{g} \times \frac{1\ \text{mol}}{180\ \text{g}} \times \frac{6\ \text{mol CO}_2}{1\ \text{mol}} \times \frac{44\ \text{g}}{1\ \text{mol}} = 14.7\ \text{g CO}_2$$

Question 1

Which of the following best describes why coefficients are used to balance chemical equations instead of changing subscripts in chemical formulas?

Accepted Answer

Changing subscripts would alter the identity of the substances involved.

Question 2

Given the reaction $$2 	ext{H}_2(g) + 	ext{O}_2(g) ightarrow 2 	ext{H}_2	ext{O}(l)$$, how many grams of water are produced from 4.00 g of hydrogen gas?

Accepted Answer

$$	ext{Molar mass of H}_2 = 2.02\ 	ext{g/mol}$$; $$	ext{Molar mass of H}_2	ext{O} = 18.02\ 	ext{g/mol}$$

$$4.00\ 	ext{g H}_2 	imes \frac{1\ 	ext{mol H}_2}{2.02\ 	ext{g H}_2} 	imes \frac{2\ 	ext{mol H}_2	ext{O}}{2\ 	ext{mol H}_2} 	imes \frac{18.02\ 	ext{g H}_2	ext{O}}{1\ 	ext{mol H}_2	ext{O}} = 35.7\ 	ext{g H}_2	ext{O}$$

Question 3

Which of the following is a decomposition reaction?

Accepted Answer

$$2	ext{KClO}_3(s) ightarrow 2	ext{KCl}(s) + 3	ext{O}_2(g)$$

Question 4

A solution is prepared by dissolving 0.50 mol of NaCl in enough water to make 1.0 L of solution. What is the molarity of the solution?

Accepted Answer

$$0.50\ 	ext{M}$$

Question 5

Which of the following compounds is a strong electrolyte when dissolved in water?

Accepted Answer

$$	ext{NaOH}$$

Question 6

What is the net ionic equation for the reaction between aqueous solutions of NaCl and AgNO$$_3$$?

Accepted Answer

$$	ext{Ag}^+(aq) + 	ext{Cl}^-(aq) ightarrow 	ext{AgCl}(s)$$

Question 7

Which of the following acids is classified as a strong acid?

Accepted Answer

$$	ext{HNO}_3$$

Question 8

A student mixes solutions of Ba(NO$$_3$$)$$_2$$ and Na$$_2SO$_4. $$What precipitate, if any, forms?

Accepted Answer

$$	ext{BaSO}_4(s)$$

Question 9

Which of the following best describes the process of dilution?

Accepted Answer

Adding solvent to decrease the concentration of solute without changing the number of moles of solute.

Question 10

How many molecules are present in 18.0 g of water ($$	ext{H}_2	ext{O}$$)? ($$	ext{Molar mass of H}_2	ext{O} = 18.0\ 	ext{g/mol}$$, $$N_A = 6.02 	imes 10$$^{23}$$)

Accepted Answer

$$6.02 	imes 10$$^{23}$$

Question 11

Which of the following is the correct balanced equation for the combustion of propane ($$	ext{C}_3	ext{H}_8$$)?

Accepted Answer

$$	ext{C}_3	ext{H}_8 + 5	ext{O}_2 ightarrow 3	ext{CO}_2 + 4	ext{H}_2	ext{O}$$

Question 12

A sample contains 61.31% C, 5.14% H, 10.21% N, and 23.33% O by mass. What is the empirical formula?

Accepted Answer

$$	ext{C}_7	ext{H}_7	ext{NO}_2$$

Question 13

Which of the following statements about redox reactions is correct?

Accepted Answer

Oxidation is the loss of electrons, and reduction is the gain of electrons.

Question 14

What is the theoretical yield of CO$$_2 (in $$grams) when 10.0 g of C$$_6H$_{12}O$_6$$ reacts completely with excess O$$_2$$? ($$	ext{C}_6	ext{H}_{12}	ext{O}_6 + 6	ext{O}_2 ightarrow 6	ext{CO}_2 + 6	ext{H}_2	ext{O}$$; $$	ext{Molar mass of C}_6	ext{H}_{12}	ext{O}_6 = 180\ 	ext{g/mol}$$; $$	ext{Molar mass of CO}_2 = 44\ 	ext{g/mol})$$

Accepted Answer

$$10.0\ 	ext{g} 	imes \frac{1\ 	ext{mol}}{180\ 	ext{g}} 	imes \frac{6\ 	ext{mol CO}_2}{1\ 	ext{mol}} 	imes \frac{44\ 	ext{g}}{1\ 	ext{mol}} = 14.7\ 	ext{g CO}_2$$

Question 15

Which of the following is a weak electrolyte?

Accepted Answer

$$	ext{CH}_3	ext{COOH}$$

Question 16

Which of the following compounds is insoluble in water according to the solubility guidelines?

Accepted Answer

$$	ext{AgCl}$$

Question 17

A solution is made by diluting 50.0 mL of 6.0 M HCl to a final volume of 300.0 mL. What is the final concentration?

Accepted Answer

$$1.0\ 	ext{M}$$

Question 18

Which of the following best describes a neutralization reaction?

Accepted Answer

A reaction between an acid and a base to produce water and a salt.

Stoichiometry and Reactions in Aqueous Solution: Study Notes for General Chemistry

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