Question

6. A 25.0-mL sample of potassium chloride solution was found to have a mass of 25.225 g.

Answer 1

Answer:

6. a. 5.53 (m/m) %; b. 0.7490M

7. 0.156M

Explanation:

6. In the solution of KCl, there are 1.396g of KCl in 25.225g of solution. As mass/mass percent is:

Mass solute / Mass solution * 100

The mass/mass percent of KCl is:

a. 1.396g KCl / 25.225g solution * 100

5.53 (m/m) %

b. Molarity is moles of solute per liters of solution:

Moles KCl -Molar mass: 74.55g/mol-:

1.396g KCl * (1mol / 74.55g) = 0.018726 moles KCl

Volume in liters: 25mL = 0.025L

Molarity:

0.018726 moles KCl / 0.025L = 0.7490M

7. 0.90% means 0.90g of NaCl in 100g of solution:

Moles NaCl -Molar mass: 58.44g/mol-:

0.90g NaCl * (1mol / 58.44g) = 0.0154 moles NaCl

Volume in Liters:

100g * (1mL / 1.01g) = 99mL = 0.099L

Molarity:

0.0154 moles NaCl / 0.099L =

0.156M