Question

a student peeled the skins from grapes, exposing cells with membranes that are only permeable to water and small diffusible solutes. the student measured the mass of the peeled grapes. the student then placed each peeled grape into one of five solutions. after 24 hours, the student removed the peeled grapes from the solutions, measured their final mass, and calculated the percent change in mass (table 1).

table 1. percent change in mass of peeled grapes in solutions

solution	concentration of solution (weight/volume)	percent change in mass
nacl	20%	-23.39%
tap water	0.8%	9.46%
grape juice	2.1%	2.8%
grape soda	13%	-15.00%

in a second experiment (table 2), the student placed a peeled grape into a solution containing both small diffusible solutes and solutes to which the membrane is impermeable (nondiffusible solutes).

based on table 1, which of the following percentages is closest to the solute concentration of the grape?
5.5%
0.0%
10.1%
1.3%

Explanation:

Step1: Understand osmosis concept

Osmosis is the movement of water across a semi - permeable membrane from an area of lower solute concentration to an area of higher solute concentration. When the solute concentration of the solution is equal to the solute concentration of the grape (isotonic condition), there is no net change in mass. When the solution is hypotonic (lower solute concentration than the grape), water enters the grape and mass increases. When the solution is hypertonic (higher solute concentration than the grape), water leaves the grape and mass decreases.

Step2: Analyze table data

We look for the solution where the percent change in mass is closest to 0%. Among the given solutions, grape juice with a 2.8% percent change in mass has a solute concentration closest to that of the grape. The solute concentration of grape juice is 2.1%. Among the options, 1.9% is the closest to 2.1%.

Answer:

1.9%