Question

Calculate molality of 28% (w/w) NaOH solution​

Answer 1

REFER TO THE ATTACHMENT FOR THE ANSWER

Answer 2

Answer:

The molality of 28% (w/w) NaOH solution is 9.72 (m).

Explanation:

What is Molality?

Molality is defined as the moles of solute dissolved in 1000 gms of solvent.

The formula for calculation of molality:

Molality can be calculated by using the following formulas:

$Molality= \frac{moles of solute}{1000 gm of solvent}$
⇒$Molality= \frac{wt. * 1000}{Mol. wt. * (wt of solvent in grams)}$

⇒$Molality= \frac{moles of solute}{wt. of solvent} * 1000$

Calculation:

28% (w/w) NaOH solution means that 28 gm of NaOH is dissolved in 100 gms. of solution.

∴ Wt. of solvent= (100 - 28) = 72 gm.

Now, the molecular weight of NaOH= 40

∴ Moles of solute (NaOH) = $\frac{28}{40} = 0.7$ moles

∴ By the problem:

Molality = $\frac{0.7}{72} * 1000 = 9.72 (m)$

Conclusion:
The molality of the resultant solution is 9.72 (m).

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