Calculate the molality of KI if the density of 20% (mass/mass) aqueous KI is 1.202 gmL -1 . Report your final answer by rounding off the molality correct upto one place of decimal and then multiplying

Question

Calculate the molality of KI if the density of 20% (mass/mass) aqueous KI is 1.202 gmL -1 . Report your final answer by rounding off the molality correct upto one place of decimal and then multiplying it by 10.

TestHub · Accepted Answer

Weight of KI in 100g of water = 20 g

Weight of water in the solution = 100 - 20 = 80 g= 0.08 kg

Molar mass of KI = 39 + 127 = 166 g mol^-1

$Molality of the solution (m) = \frac{Number of moles of KI}{Mass of water in kg}$

$= \frac{(20 g) / (166 g {mol}^{- 1})}{(0 \cdot 08 kg)}$

= 1.506 mol kg^-1= 1.506 m

By rounding off to one place, we get the molality as 1.5 and by further multiplying it with 10, we get "15" as the final answer.

Chemistry - Mole Concept Question with Solution | TestHub

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