Question

What would be the molality of $20\%$ (mass / mass) aqueous solution of $KI$? (molar mass of $KI = 166\, g\, mol^{-1}$)

• A. 1.08
• B. 1.48
• C. 1.51
• D. 1.35

Answer 1

Answer: (C)

1.51

Answer 2

$\frac{W}{W} \% = 20$
$100\, gm$ solution has $20\, gm\, KI$
$80 \,gm$ solvent has $20\, gm\, KI$
$m = \frac{\frac{20}{166}}{\frac{80}{1000}} = \frac{20\times1000}{166\times80} = 1.506 \simeq 1.51 \,mol/kg$