Chapter 13 - The Chemistry of Solutes and Solutions - Questions for Review and Thought - Topical Questions - Page 605c: 53

0.80 g

Given: Molality= 0.050 mol/kg and Mass of the solvent=500. g = 0.500 kg Recall: Molality=$\frac{moles\, of\,solute}{mass\, of\, solvent\,in\,kg}$ $\implies$ moles of methanol= Molality$\times$ mass of solvent in kg $=0.050\,mol/kg\times 0.500\,kg=0.025\,mol$ Mass of methanol needed = number of moles$\times$ molar mass $=0.025\,mol\times 32\,g/mol=0.80\,g$