The molality is 2.83 molal. The definition of molality is moles of solute per kilograms of solvent. The substance present in fewer moles is the solute and the substance present in higher moles relative to the solute is the solvent. In this case, lead is the solute since we have .332 moles of lead and .986 moles of tin. We find the amount of moles by performing the following calculation: 68.7g lead/207.2 g/mol lead=.332 moles of lead. molality=moles solute/kg solvent. In this case, we have 117g X 1kg/1000g= .117 kg. .332 moles of lead solute/ .117 kg tin solvent =2.83 molal
