Question

How many moles of solute would be dissolved in .500 kg of solvent to make a 2.50 molal NaOH solution?

Answer 1

Molality is a measure of concentration that relates the moles of solute to the kilograms of solvent, it is described by the following equation:

$Molality=\frac{molSolute}{kgSolvent}$

We are given the molality(2.50m) and kilograms of solvent(0.500kg), so we solve for moles of solute from the equation:

$molSolute=Molality\times kgSolvent$$\begin{gathered} molSolute=2.50m\times0.500kg \\ molSolute=1.25molSolute \end{gathered}$

To make a 2.50molal NaOH solution would be needed 1.25moles of solute

Answer: 1.25 moles