What is the mass percent of alcohol in a solution containing 62 mL of ethyl alcohol mixed into 200 mL of water? (Note: Density of ethyl alcohol = 0.8 g/mL; density of water = 1 g/mL.)

Question

What is the mass percent of alcohol in a solution containing 62 mL of ethyl alcohol mixed into 200 mL of water?  (Note: Density of ethyl alcohol = 0.8 g/mL; density of water = 1 g/mL.)

Quizplus · Accepted Answer

11ecba2d_1249_bdc1_a3bf_39405d533dc5_MD0008_00 Percentages can be used to express the elemental composition of a molecule or the concentration of a given component within a solution mixture. However, a variety of different ratios can be chosen as the basis for calculating a percentage. When a mass ratio is used to calculate the percentage, it is called a mass percent (% m/m), defined as the component mass divided by the total mass of the formula unit or mixture expressed as a percentage. 11ecba2d_1249_e4d2_a3bf_d140fad438cd_MD0008_00 % m/m=component masstotal mass×100 In a solution mixture, the total mass of the solution is the combined mass of the dissolved component(s) (solute) and the mass of the solvent. 11ecba2d_1249_e4d3_a3bf_a56c7f4b130d_MD0008_00 When the solvent (or solute) of a solution is a liquid that are measured as a volume, the density of each liquid must be used to find the mass contained in each volume prior to completing a mass percent calculation. The density of a substance specifies the mass it contains per unit of volume that it occupies. Applying the densities given in this question, 62 mL of ethyl alcohol and 200 mL of water equate to the following amounts of mass: 11ecba2d_1249_e4d4_a3bf_138bc9a7968f_MD0008_00 11ecba2d_1249_e4d5_a3bf_dd1373e05528_MD0008_00 Using these masses, the mass percent of the alcohol in the solution is calculated to be: 11ecba2d_1249_e4d6_a3bf_af918a744524_MD0008_00 (Choice A) A solution containing only 48 mL of ethyl alcohol in 200 mL of water is 16% (m/m) alcohol. (Choice C) A value of 25% results from dividing the mass of the alcohol by the mass of the water rather than by the total mass of the alcohol and water. (Choice D) A value of 31% results from dividing the volume of the alcohol by the volume of the water rather than calculating the ratio of the alcohol mass to the total solution mass. Educational objective: Mass percent (% m/m) is defined as the component mass divided by the total mass of the formula unit or mixture expressed as a percentage. The total mass of a solution mixture equals the combined mass of solute and the solvent, and the density of a liquid must be used to find its mass to complete a mass percent calculation.

What Is the Mass Percent of Alcohol in a Solution