Q: A solution is prepared by dissolving 14.0 g of NaCl in enough water to make 100 g of solution. What is the mass percent (m/m) of NaCl in the solution?

$$\frac{14.0\ g}{100\ g} \times 100\% = 14.0\%$$

Q: A chemist wants to prepare 1.00 L of a 1.00 M NaCl solution. What mass of NaCl should be used?

$$1.00\ mol \times 58.44\ g/mol = 58.44\ g$$

Q: A student needs to prepare 100.0 mL of 3.00 M NaOH from a 15.0 M stock solution. What volume of the stock solution should be used?

$$V_1$$ = \frac{$$M_2$$ $$V_2$$}{$$M_1$$} = \frac{3.00\ M \times 100.0\ mL}{15.0\ M} = 20.0\ mL$$

Question 1

Which of the following best describes a homogeneous mixture, as shown in the study materials?

Accepted Answer

A mixture in which the composition is uniform throughout, such as tea with sugar.

Question 2

A solution is prepared by dissolving 14.0 g of NaCl in enough water to make 100 g of solution. What is the mass percent (m/m) of NaCl in the solution?

Accepted Answer

$$\frac{14.0\ g}{100\ g} 	imes 100\% = 14.0\%$$

Question 3

Which of the following statements about the dissolution of ionic compounds in water is correct?

Accepted Answer

Ions are pulled away from the crystal and surrounded by water molecules, which insulate them from each other.

Question 4

A chemist wants to prepare 1.00 L of a 1.00 M NaCl solution. What mass of NaCl should be used?

Accepted Answer

$$1.00\ mol 	imes 58.44\ g/mol = 58.44\ g$$

Question 5

Which of the following is a strong electrolyte?

Accepted Answer

A soluble ionic compound such as NaCl.

Question 6

What is the molarity of a solution made by dissolving 90.0 g of ammonium dichromate $$(NH_4$)_2Cr_2O_7 ($$molar mass = 252.10 g/mol) in enough water to make 250.0 mL of solution?

Accepted Answer

$$\frac{90.0\ g}{252.10\ g/mol} \div 0.2500\ L = 1.43\ M$$

Question 7

How many liters of a 0.125 M NaOH solution are needed to provide 0.255 mol NaOH?

Accepted Answer

$$\frac{0.255\ mol}{0.125\ M} = 2.04\ L$$

Question 8

A student needs to prepare 100.0 mL of 3.00 M NaOH from a 15.0 M stock solution. What volume of the stock solution should be used?

Accepted Answer

$$V_1$$ = \frac{$$M_2$$ $$V_2$$}{$$M_1$$} = \frac{3.00\ M 	imes 100.0\ mL}{15.0\ M} = 20.0\ mL$$

Question 9

Which of the following best describes the role of spectator ions in a precipitation reaction?

Accepted Answer

They do not participate in the formation of the precipitate and remain unchanged in solution.

Question 10

Which of the following is the correct net ionic equation for the reaction between KOH(aq) and Mg(NO$$_3$$)$$_2(aq) to $$form Mg(OH)$$_2(s$$)?

Accepted Answer

$$\mathrm{Mg$$^{2+}$$ (aq) + 2OH^- (aq) \rightarrow Mg(OH)_2 (s)}$$

Question 11

Which of the following is a correct statement about the solubility rules for ionic compounds?

Accepted Answer

All compounds containing Group 1A metals or ammonium are soluble in water.

Question 12

A solution is labeled as 25.6% ethanol (v/v). What does this mean?

Accepted Answer

There are 25.6 mL of ethanol in every 100 mL of solution.

Question 13

Which of the following best explains why the total volume of a solution is not always the sum of the volumes of solute and solvent added?

Accepted Answer

Solute and solvent particles interact and pack more efficiently, reducing the total volume.

Question 14

Which of the following is a real-life example of a heterogeneous mixture?

Accepted Answer

Wet sand collected from a beach.

Question 15

A precipitation reaction occurs when aqueous solutions of potassium carbonate and nickel(II) chloride are mixed. Which compound precipitates?

Accepted Answer

Nickel(II) carbonate, NiCO$$_3$$

Question 16

Which of the following is the correct balanced molecular equation for the reaction between K$$_2CO$_3(aq) $$and NiCl$$_2(aq$$)?

Accepted Answer

$$\mathrm{K_2CO_3 (aq) + $$NiCl_2$$ (aq) \rightarrow 2KCl (aq) + $$NiCO_3$$ (s)}$$

Question 17

Which of the following best describes a weak electrolyte?

Accepted Answer

A substance that partially ionizes in water, such as acetic acid.

Reactions in Aqueous Solutions and Solution Stoichiometry

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