Question

1A. What Volume of 25.0% glucose must be used to make 925 mL of 3.75% glucose?

1B. If a solution is prepared by dissolving 106.0 g of NaCl in enough water to make 980.0 mL of solution, what is the %(w/v) of NaCl?

1C. How much glucose must be used to prepare 525 mL of a 6.85% (w/v) solution?

1D. What is the % of (w/w) of a NaOH solution prepare by dissolving 52.4 g of NaOH in 395.0 g of water?

Answer 1

A)

use dilution formula

M1*V1 = M2*V2

1---> is for stock solution

2---> is for diluted solution

Given:

M1 = 25 %

M2 = 3.75 %

V2 = 925 mL

use:

M1*V1 = M2*V2

V1 = (M2 * V2) / M1

V1 = (3.75*925)/25

V1 = 139 mL

Answer: 139 mL

B)

%(w/v) = mass of solute * 100 / volume of solution

= 106.0 * 100 / 980.0

= 10.81 %

Answer: 10.81 %

C)

%(w/v) = mass of solute * 100 / volume of solution

6.85 = mass of solute * 100 / 525

mass of solute = 36.0 g

Answer: 36.0 g

D)

%(w/w) = mass of solute * 100 / mass of solution

= 52.4 * 100 / (52.4 + 395.0)

= 11.7 %

Answer: 11.7 %