A 4 g sugar cube (Sucrose: C12H22O11) is dissolved in a 350 ml teacup of 80 °C water. What is the percent composition by mass of the sugar solution?
Given: Density of water at 80 °C = 0.975 g/ml
Step 1 - Determine mass of solute
We were given the mass of the solute in the problem. The solute is the sugar cube.
masssolute = 4 g of C12H22O11
Step 2 - Determine mass of solvent
The solvent is the 80 °C water. Use the density of the water to find the mass.
density = mass/volume
mass = density x volume
mass = 0.975 g/ml x 350 ml
masssolvent = 341.25 g
Step 3 - Determine the total mass of the solution
msolution = msolute + msolvent
msolution = 4 g + 341.25 g
msolution = 345.25 g
Step 4 - Determine percent composition by mass of the sugar solution.
percent composition = (msolute / msolution) x 100
percent composition = ( 4 g / 345.25 g) x 100
percent composition = ( 0.0116 ) x 100
percent compostion = 1.16%
The percent composition by mass of the sugar solution is 1.16%