Q: A solution is prepared by mixing 15.0 g of Na$$_2CO$_3$$ and 235 g of H$$_2O. $$What is the mass percent (w/w%) of Na$$_2CO$_3 in $$the solution?

$$\frac{15.0}{15.0 + 235} \times 100\% = 6.00\%$$

Q: How many grams of NaOH are needed to prepare 75.0 g of a 14.0% (w/w) NaOH solution?

$$75.0 \times \frac{14.0}{100} = 10.5 g$$

Q: A 0.50 L sample of 6.0 M HCl solution is diluted to a final volume of 1.0 L. What is the final concentration?

$$M_2$$ = \frac{$$M_1$$ $$V_1$$}{$$V_2$$} = \frac{6.0 \times 0.50}{1.0} = 3.0$$ M

Q: A solution is prepared by mixing 25 mL of alcohol (density = 0.8 g/mL) with 50 mL of H$$_2O ($$density = 1.0 g/mL). What is the mass/volume percent (m/v%) of alcohol in the solution?

$$\frac{25 \times 0.8}{75} \times 100\% = 26.7\%$$

Question 1

Which of the following best describes a solution?

Accepted Answer

A homogeneous mixture of two or more substances

Question 2

A solution is prepared by mixing 15.0 g of Na$$_2CO$_3$$ and 235 g of H$$_2O. $$What is the mass percent (w/w%) of Na$$_2CO$_3 in $$the solution?

Accepted Answer

$$\frac{15.0}{15.0 + 235} 	imes 100\% = 6.00\%$$

Question 3

Which of the following statements about electrolytes is correct?

Accepted Answer

Nonelectrolytes do not produce ions in water

Question 4

How many grams of NaOH are needed to prepare 75.0 g of a 14.0% (w/w) NaOH solution?

Accepted Answer

$$75.0 	imes \frac{14.0}{100} = 10.5 g$$

Question 5

What is the molarity of a solution made by dissolving 5.0 g of NaCl (molar mass = 58.44 g/mol) into 250 mL of water?

Accepted Answer

$$M = \frac{5.0/58.44}{0.250} = 0.342 M$$

Question 6

A 0.50 L sample of 6.0 M HCl solution is diluted to a final volume of 1.0 L. What is the final concentration?

Accepted Answer

$$M_2$$ = \frac{$$M_1$$ $$V_1$$}{$$V_2$$} = \frac{6.0 	imes 0.50}{1.0} = 3.0$$ M

Question 7

Which of the following best explains why NaCl is a strong electrolyte?

Accepted Answer

It dissociates completely into ions in water

Question 8

A solution is prepared by mixing 25 mL of alcohol (density = 0.8 g/mL) with 50 mL of H$$_2O ($$density = 1.0 g/mL). What is the mass/volume percent (m/v%) of alcohol in the solution?

Accepted Answer

$$\frac{25 	imes 0.8}{75} 	imes 100\% = 26.7\%$$

Question 9

Which of the following mixtures is a colloid?

Accepted Answer

Milk

Question 10

Which of the following best describes osmosis?

Accepted Answer

The movement of solvent from low to high solute concentration through a semipermeable membrane

Question 11

A red blood cell is placed in a hypotonic solution. What will happen to the cell?

Accepted Answer

It will swell and may burst due to water entering the cell (hemolysis)

Question 12

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

Accepted Answer

PbI$$_2$$

Question 13

Calculate the number of moles of NaCl in 750.0 mL of 3.00 M NaCl solution.

Accepted Answer

$$n = 3.00 	imes 0.750 = 2.25$$ mol

Question 14

Which of the following best describes an isotonic solution with respect to red blood cells?

Accepted Answer

It exerts the same osmotic pressure as RBCs, so the cells retain their normal shape

Question 15

What is the pH of a solution with $$[H^+] = 8.5 	imes 10$$^{-4}$$ M?

Accepted Answer

$$pH = -\log(8.5 	imes 10$$^{-4}$$) = 3.07$$

Question 16

Which process is used in desalination plants to obtain pure water from seawater?

Accepted Answer

Reverse osmosis

Question 17

A solution is prepared by diluting 10.0 mL of 5.0% NaOH to 250.0 mL. What is the new percent (w/w%) of NaOH?

Accepted Answer

$$\frac{10.0 	imes 5.0}{250.0} = 0.20\%$$

Question 18

Which of the following best explains why water is a polar solvent?

Accepted Answer

It has polar O—H bonds and bent geometry

Question 19

Which of the following statements about dialysis is correct?

Accepted Answer

Both solvent and small solute particles pass through the membrane

Chapter 9: Solutions – General Chemistry Study Notes

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