# What is the mole fraction of KI in a solution made by dissolving 3.4 g of KI in 5.8 g of water?

Jan 5, 2017

$\text{Mole fraction}$ $=$ $\text{Moles of component"/"Moles of all species in solution}$

#### Explanation:

And thus, $\text{Mole fraction, KI}$ $=$ $\text{Moles of KI"/"Moles of KI + moles of water}$

$= \frac{\frac{3.4 \cdot g}{166.00 \cdot g \cdot m o {l}^{-} 1}}{\frac{3.4 \cdot g}{166.00 \cdot g \cdot m o {l}^{-} 1} + \frac{5.8 \cdot g}{18.01 \cdot g \cdot m o {l}^{-} 1}}$ $=$ $0.060$

Note that the mole fraction of $\text{water}$ here must be necessarily $1 - 0.060 = 0.94$. Why $\text{necessarily}$?

Note that $\text{mole fractions}$, as they are here, are dimensionless quantities.