Question

The concentration of Kbr in a solution prepared by dissolving 4.21g of KBr in 797g of water is ______ molal

Answer 1

To determine the molal concentration we:

`\begin{gathered} molality=\frac{moles\text{ }solute}{kg\text{ }solvent} \\ \\ moles=\frac{mass}{molar\text{ }mass} \\ \\ _nKBr=(4.21g)/(119gmol^(-1)) \\ _nKBr=0.0354mol \\ \\ molality=(0.0354mol)/(0.797kg) \\ molality=0.044m \end{gathered}`

Answer: 0.044 molal