Question

PLEASE HELP ME FIND SOLUTION OF THIS---
The density of 2 M aqueous solution of NaOH is 1.28 g/cm3. The molality of the solution is [Given that molecular mass of NaOH = 40 g mol–1]

Answer 1

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Answer 2

Given that, the density of 2 M aqueous solution of NaOH is 1.28 g/cm³.

{ Density (d) is 1.28 g/cm³ and Molarity (M) is 2M }

We have to find molality (m) of the solution.

Now,

The relation between Molality, Molarity and Density is:

m = 1000M/(1000d - 2m.m.)

Here, m = molality, M = Molarity, d = density and m.m. = molar mass

Also given that, Molar Mass (m.m.) of NaCl = 40 g/mol

Substitute the known values in the above formula,

→ m = [1000(2)]/[1000(1.28) - 2(40)]

→ m = 2000/(1280.00 - 80)

→ m = 2000/(1280 - 80)

→ m = 2000/1200

→ m = 20/12

→ m = 5/3

→ m = 1.67

Therefore, the molality of the solution is 1.67 Molal.