Question

A 150ml of 0.15 M NaCl solution is added to another 250 ml of 0.2M NaCl solution and the resulting solution was mixed with a 150 ml NaCl solution of unknown molarity. molarity of the final solution was formed to be 0.25M. then the unknown molarity of the solution is

Answer 1

1.15 is the molality of the unknown solution

Answer 2

Given:

M1 = 0.15 M

V1 = 150 ml

M2 = 0.2 M

V2 = 250 ml

V3 = 150 ml

M = 0.25 M

To Find:

The unknown molarity of NaCl solution, i,e., M3.

Calculation:

- Total Volume, V = V1 + V2 + V3

V = 150 + 250 + 150 = 550 ml

- Using the molarity equation, we get:

MV = M1V1 + M2V2 + M3V3

⇒ 0.25 × 550 = 0.15 × 150 + 0.2 × 250 + M3 × 150

⇒ 137.5 = 22.5 + 50 + 150 M3

⇒ M3 = (137.5 - 72.5) / 150

⇒ M3 = 65/150

⇒ M3 = 0.433 M

- So, the unknown molarity of the NaCl solution is 0.433 M.