Chemistry - Concentration Terms Question with Solution | TestHub

1 mole of solute present in $1\mathrm{kg}$ of ${\mathrm{H}}_2\mathrm{O}$ 1 mole of solute present in $\frac{1000}{18}\mathrm{g}$. mole of ${\mathrm{H}}_2\mathrm{O}$ $$\begin{array}{rl}{\mathrm{X}}_{\text{solute }}& =\frac{1}{\frac{1000}{18}+1}=\frac{18}{1018}\\ & =0.01768\approx \mathrm{0.018.}\end{array}$$ Related Theory The molar fraction can be represented by $X$. If the solution consists of components $A$ and $B$, then the mole fraction is, Mole fraction of solute $$=\frac{\text{ Moles of Solute }}{\text{ Moles of Solute }+\text{ Moles of Solven }}$$ $$=\frac{n_A}{n_A+n_B}$$ Mole fraction of solute $=\frac{n_B}{n_A+n_B}$ Therefore, the sum of mole fraction of all the components is always equal to one. Caution Students misread the word 'molal' as 'molar'.