Homework Answers

6. How many moles of sucrose 𝐶₁₂𝐻₂₂𝑂₁₁, are contained in 50.0g of a 0.85 m sucrose solution?

7. What volume of 0.25 M NaOH contains 0.050 mol NaOH?

8. What mass of sodium phosphate is dissolved in 255g of a solution that is 20.0% by mass 𝑁𝑎₃𝑃𝑂₄?

9. A 375.0g sample of river water taken near an industrial plant contains 37mg of chromium.

a. What is the mass percent of chromium in the river?

b. How many parts per million of chromium are in the river?

c. How many parts per billion?

10. If a solution of 𝐴𝑔𝑁𝑂₃ is added to an HCl solution, insoluble AgCl will precipitate:

𝐴𝑔𝑁𝑂₃ (𝑎𝑞) + 𝐻𝐶𝑙(𝑎𝑞) → 𝐴𝑔𝐶𝑙(𝑠) + 𝐻𝑁𝑂₃(𝑎𝑞)

What volume of a 1.20 M 𝐴𝑔𝑁𝑂₃ solution must be added to 250.0 mL of a 0.100 M HCl solution to precipitate all the chlorine ion?

1. Consider a solution prepared by adding 2.70 g of acetic acid(𝐶𝐻₃𝐶𝑂₂𝐻), to 122.8 g of water.

a. What is the percent by mass concentration of acetic acid in this solution?

b. What mass of acetic acid is present in 25.0g of this solution?

2. To prepare a solution, we dissolve 205 mL of ethanol in sufficient water to give a total volume of 235mL. What is the percent-by-volume concentration of ethanol?

3. What is the concentration in ppm of selenium if 0.020g is found in 5.0 × 10³𝑘𝑔 of soil?

4. A solution contains 117g of potassium hydroxide (KOH), dissolved in sufficient water to give a total volume of 2.00 L. The molar mass of KOH is 56.11 𝑔/𝑚𝑜𝑙 . What is the molarity of the aqueous potassium hydroxide solution?

5. A solution contains 22.5g of methanol(𝐶𝐻₃𝑂𝐻), dissolved in sufficient water to give a total mass of 105.3g. The molar mass of 𝐶𝐻₃𝑂𝐻 is 32. 𝑔/𝑚𝑜𝑙 . What is the molality of the aqueous methanol solution?

1. When a solution of lead(II) nitrate is mixed with a solution of potassium chromate, a yellow precipitate forms according to the equation.

𝑃𝑏(𝑁𝑂₃ )₂ (𝑎𝑞) + 𝐾₂𝐶𝑟𝑂₄ (𝑎𝑞) → 𝑃𝑏𝐶𝑟𝑂₄ (𝑠) + 2𝐾𝑁𝑂₃

(a)What volume of 0.105 M lead (II) nitrate is required to react with 100 mL of 0.120 M potassium chromate

(b)What mass of 𝑃𝑏𝐶𝑟𝑂₄ solid forms?

2. Suppose a titration is run in which 25.05 mL of NaOH solution of unknown concentration reacts with 25.00 mL of 0.1000 M 𝐻₂𝑆𝑂₄ solution. The chemical equation that summarizes the reaction is as follows:

𝐻₂𝑆𝑂₄ (𝑎𝑞) + 2𝑁𝑎𝑂𝐻(𝑎𝑞) → 2𝐻₂𝑂(𝑙) + 𝑁𝑎₂𝑆𝑂₄(𝑎𝑞)

What is the molarity of the solution?

3. If a solution of 𝐴𝑔𝑁𝑂₃ is added to an HCl solution, insoluble AgCl will precipitate:

𝐴𝑔𝑁𝑂₃ (𝑎𝑞) + 𝐻𝐶𝑙(𝑎𝑞) → 𝐴𝑔𝐶𝑙(𝑠) + 𝐻𝑁𝑂₃(𝑎𝑞)

(a)What volume of 1.20 M 𝐴𝑔𝑁𝑂₃ solution must be added to 250.0 mL of a 0.100 M HCl solution to precipitate all the chloride ion?

(b)What mass of AgCl should precipitate?