What mass of cesium chloride must be added to 0.565 L water to produce a 0.355 m solution?

Question

What mass of cesium chloride must be added to 0.565 L water to produce a 0.355 m solution? (Assume d of H2O = 1.00 g/mL.)
_________g

What are the mole fraction and the mass percent of CsCl?

how do i use the molar mass to find the amount of solute

Answer 1

For the first part, you know that m is molality. The units of molality are mol solute / kg solvent. Since the density of water is 1 g/mL, multiply the desired molality by the volume of the solvent (in L) to give you the needed moles of water. Then, use CsCl's molar mass to calculate the mass of CsCl needed.

To calculate the mass percent, divide the mass of CsCl by the combined mass of the solute and the solvent. Multiply that number by 100 to make it a percentage.

For the mole fraction, calculate the number of moles of water in 565 grams of water. Divide the moles of CsCl used in the solution by the sum of the moles of water + moles of CsCl.