Question

A 0.610 m aqueous solution of kbr has a total mass of 75.0 g. what masses of solute and solvent are present?

Answer 1

To find the mass of solute and solvent in a KBr solution, calculate the moles of KBr using the molarity and volume, convert to grams using the molar mass of KBr, and subtract from the total mass of the solution to get the mass of the solvent.

Step-by-step explanation:

The question is asking about the calculation of masses of solute and solvent in an aqueous KBr solution with a known molarity and total mass. We understand that molarity (M) is defined as moles of solute per liter of solution. The formula to use would be:

M = moles of solute / liters of solution

Firstly, to find the mass of solute, we need to calculate the number of moles of KBr using the molarity and volume of the solution, and then convert these moles to grams using the molar mass of KBr. The mass of the solvent (water) can be found by subtracting the mass of the solute from the total mass of the solution. To illustrate:

Moles of KBr = molarity × volume of solution (in liters)

Mass of KBr = Moles of KBr × molar mass of KBr

Mass of solvent (water) = Total mass of solution - Mass of solute (KBr)

Answer 2

To determine the masses of each component, we need to know the concentration first in terms of molality which is mol per mass of solution. Assuming the density of the solution is equal to that of water we would find:

molality = 0.160 mol KBr / L ( 1 L / 1 kg solution ) = 0.160 mol KBr / kg solution

mass KBr = 0.160 mol KBr / kg solution (.0750 kg solution ) ( 119 g KBr / mol KBr ) = 1.428 g KBr

mass solvent = 75 - 1.428 = 73.572 g water