Question

how many gram of KCL must be added to 75 gram of water to produce a solution that 2.25 molal​

Answer 1

Answer : The mass of KCl added must be, 12.58 grams

Explanation :

Molality : It is defined as the number of moles of solute present in one kilogram of solvent.

In this question, the solute is KCl and solvent is water.

Formula used :

$Molality=\frac{w_b}{M_b\times w_a}\times 1000$

where,

Molality = 2.25 mole/Kg

$w_a$ = mass of solvent (water) = 75 g

$w_b$ = mass of solute KCl = ?

$M_b$ = molar mass of solute KCl = 74.55 g/mole

Now put all the given values in the above formula, we get the mass of hydrogen peroxide.

$2.25mole/Kg=\frac{w_b}{74.55g/mole\times 75g}\times 1000$

$w_b=12.58g$

Therefore, the mass of KCl added must be, 12.58 grams