A solution prepared by dissolving 20.2 mL of CH3OH in 100mL of water @ 25 celcius. The final volume of the solution is 118 mL. Calculate the % by mass.
density CH3OH[0.782g/mL], H20[1g/mL] @ room temp.
To calculate the percentage by mass of the solution, we need to find the mass of each component.
The mass of CH3OH can be calculated using its density and volume:
mass_CH3OH = volume_CH3OH x density_CH3OH
mass_CH3OH = 20.2 mL x 0.782 g/mL
mass_CH3OH = 15.7964 g
The mass of water can be calculated using its density and volume:
mass_water = volume_water x density_water
mass_water = 100 mL x 1 g/mL
mass_water = 100 g
The total mass of the solution is the sum of the masses of CH3OH and water:
total_mass = mass_CH3OH + mass_water
total_mass = 15.7964 g + 100 g
total_mass = 115.7964 g
Finally, we can calculate the percentage by mass:
% by mass = (mass_CH3OH / total_mass) x 100%
% by mass = (15.7964 g / 115.7964 g) x 100%
% by mass ≈ 13.65%
Therefore, the percentage by mass of the solution is approximately 13.65%.