Q: A nurse needs to prepare 250 mL of a 2.0% (m/v) saline solution. How many grams of NaCl are required?

$$2.0\ \% = \frac{\text{grams NaCl}}{250\ \text{mL}} \times 100$$ $$\Rightarrow \text{grams NaCl} = \frac{2.0 \times 250}{100} = 5.0 g$$

Q: A 0.10 M NaCl solution is diluted to a final volume that is five times the original volume. What is the new concentration?

$$C_2$$ = $$C_1$$ \times \frac{$$V_1$$}{$$V_2$$} = 0.10\ \text{M} \times \frac{1}{5} = 0.020\ \text{M}$$

Q: A patient receives an intravenous solution containing 5.0% (m/v) glucose. If the molar mass of glucose is 180 g/mol, what is the molarity of the solution?

$$5.0\ \% = 5.0\ \text{g}/100\ \text{mL} = 50\ \text{g}/1\ \text{L}$$ $$\text{Molarity} = \frac{50\ \text{g}}{180\ \text{g/mol}} = 0.28\ \text{M}$$

Q: A solution is made by dissolving 0.75 mol of KBr in 1.0 kg of water. What is the boiling point of the solution? (Assume KBr is a strong electrolyte and the boiling point elevation constant for water is $$0.51\ ^\circ\text{C}/\text{mol})$$

$$\Delta T_b = i \cdot K_b \cdot m = 2 \times 0.51 \times 0.75 = 0.77\ ^\circ\text{C}$$ $$T_b = 100.00 + 0.77 = 100.77\ ^\circ\text{C}$$

Q: A glass of water contains 400 mL. What is the maximum mass of chloroform (in grams) allowed if the safe limit is 100 ppb?

$$100\ \text{ppb} = 100\ \frac{\text{g}}{10^9$\ \text{g}}$$ $$\text{Mass} = 400\ \text{g} \times \frac{100}{10^9$} = 4.0 \times 10$$^{-5}$$\ \text{g}$$

Q: A solution is prepared by dissolving 2.355 g of $$\mathrm{H_2SO_4} in $$water and diluting to a final volume of 50.0 mL. What is the molarity of the solution? (Molar mass of $$\mathrm{H_2SO_4} = 98.1 g/$$mol)

$$\text{Moles} = \frac{2.355}{98.1} = 0.0240$$ mol $$\text{Volume} = 0.0500 L$$ $$M = \frac{0.0240}{0.0500} = 0.480 M$$

Question 1

Which of the following best describes why oil and water do not mix, even after vigorous shaking?

Accepted Answer

Oil is nonpolar and water is polar, so their intermolecular forces are too dissimilar to allow mixing.

Question 2

A solution is prepared by dissolving 10.0 g of NaCl in 100 mL of water at 25 °C. Which term best describes the NaCl in this solution?

Accepted Answer

Solute

Question 3

Which of the following statements about the effect of temperature on solubility is correct?

Accepted Answer

The solubility of most solids increases with increasing temperature, while the solubility of gases decreases.

Question 4

A nurse needs to prepare 250 mL of a 2.0% (m/v) saline solution. How many grams of NaCl are required?

Accepted Answer

$$2.0\ \% = \frac{	ext{grams NaCl}}{250\ 	ext{mL}} 	imes 100$$ 
$$\Rightarrow 	ext{grams NaCl} = \frac{2.0 	imes 250}{100} = 5.0 g$$

Question 5

A 0.10 M NaCl solution is diluted to a final volume that is five times the original volume. What is the new concentration?

Accepted Answer

$$C_2$$ = $$C_1$$ 	imes \frac{$$V_1$$}{$$V_2$$} = 0.10\ 	ext{M} 	imes \frac{1}{5} = 0.020\ 	ext{M}$$

Question 6

Which of the following best explains why a solution of NaCl in water conducts electricity, but a solution of sugar in water does not?

Accepted Answer

NaCl dissociates into ions in water, making it a strong electrolyte, while sugar does not produce ions.

Question 7

A patient receives an intravenous solution containing 5.0% (m/v) glucose. If the molar mass of glucose is 180 g/mol, what is the molarity of the solution?

Accepted Answer

$$5.0\ \% = 5.0\ 	ext{g}/100\ 	ext{mL} = 50\ 	ext{g}/1\ 	ext{L}$$ 
$$	ext{Molarity} = \frac{50\ 	ext{g}}{180\ 	ext{g/mol}} = 0.28\ 	ext{M}$$

Question 8

Which of the following statements about colligative properties is correct?

Accepted Answer

Colligative properties depend on the number of solute particles, not their chemical identity.

Question 9

A solution is made by dissolving 0.75 mol of KBr in 1.0 kg of water. What is the boiling point of the solution? (Assume KBr is a strong electrolyte and the boiling point elevation constant for water is $$0.51\ ^\circ	ext{C}/	ext{mol})$$

Accepted Answer

$$\Delta T_b = i \cdot K_b \cdot m = 2 	imes 0.51 	imes 0.75 = 0.77\ ^\circ	ext{C}$$ 
$$T_b = 100.00 + 0.77 = 100.77\ ^\circ	ext{C}$$

Question 10

A glass of water contains 400 mL. What is the maximum mass of chloroform (in grams) allowed if the safe limit is 100 ppb?

Accepted Answer

$$100\ 	ext{ppb} = 100\ \frac{	ext{g}}{10^9$\ 	ext{g}}$$ 
$$	ext{Mass} = 400\ 	ext{g} 	imes \frac{100}{10^9$} = 4.0 	imes 10$$^{-5}$$\ 	ext{g}$$

Question 11

A solution is prepared by dissolving 2.355 g of $$\mathrm{H_2SO_4} in $$water and diluting to a final volume of 50.0 mL. What is the molarity of the solution? (Molar mass of $$\mathrm{H_2SO_4} = 98.1 g/$$mol)

Accepted Answer

$$	ext{Moles} = \frac{2.355}{98.1} = 0.0240$$ mol 
$$	ext{Volume} = 0.0500 L$$ 
$$M = \frac{0.0240}{0.0500} = 0.480 M$$

Question 12

A patient’s blood contains 5.0 mEq/L of $$\mathrm{K^+}. $$How many milligrams of $$\mathrm{K^+}$$ are in 1.00 L of blood? (Molar mass of $$\mathrm{K^+} = 39.1 g/$$mol)

Accepted Answer

$$5.0\ 	ext{mEq} = 0.005\ 	ext{Eq}$$ 
$$1\ 	ext{Eq} = 1\ 	ext{mol charge}$$ 
$$	ext{Moles} = 0.005$$ mol 
$$	ext{Mass} = 0.005 	imes 39.1 = 0.196 g$$ $$= 196 mg$$

Question 13

Which of the following best describes the process of osmosis in biological systems?

Accepted Answer

The movement of solvent molecules through a semipermeable membrane from a region of lower solute concentration to higher solute concentration.

Question 14

A red blood cell is placed in a solution with an osmolarity much lower than that of blood plasma. What will happen to the cell?

Accepted Answer

Water will enter the cell by osmosis, causing it to swell and possibly burst.

Question 15

Which of the following is a correct application of Henry’s Law?

Accepted Answer

The solubility of a gas in a liquid increases as the partial pressure of the gas above the liquid increases.

Question 16

A dialysis membrane is used in hemodialysis to treat kidney failure. Which of the following best describes what passes through the membrane?

Accepted Answer

Small solute particles and solvent molecules, but not proteins or blood cells.

Question 17

A solution is prepared by dissolving 1.8 g of heparin sodium in enough water to make 15 mL of solution. What is the (m/v)% concentration?

Accepted Answer

$$(m/v)\% = \frac{1.8\ 	ext{g}}{15\ 	ext{mL}} 	imes 100 = 12\%$$

Question 18

Which of the following pairs of substances would you expect to be miscible in all proportions?

Accepted Answer

Ethanol and water

Chapter 9: Solutions – Study Guide for GOB Chemistry

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