Question

If mass percentage of methyl alcohol in aqueous solution is 16% then molality of the solution will be
1)7.25m
2)3.15m
3)8.23m
4)5.95m​

Answer 1

Answer:

4)5.95m

Explanation:

Since , concentration units don't depend upon amount of substance . So, we can take any amount of them as per our convenience. So, we took 100g of solution .

Answer 2

Answer:

4) 5.95m​

Explanation:

Given that :

Methyl alcohol is 16 % w/w in solution.  

It means that 16 g of methyl alcohol is present in 100 g of the solution.  

Mass of water = 100 - 16 g = 84 g = 0.084 kg

Molar of methyl alcohol = 32.04 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{16\ g}{32.04\ g/mol}$

Moles = 0.4994 moles

Molality is defined as the moles of the solute present in 1 kilogram of the solvent.

So, molality is:

$m=\frac {0.4994\ moles}{0.084\ kg}$

Molality = 5.95 m