A large beaker contains two different mixtures prepared by a student during a…
CHEMISTRY · Multi-part · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
A large beaker contains two different mixtures prepared by a student during a laboratory period. Mixture 1 was obtained by completely dissolving 90.0 g of sucrose (table sugar) in enough water to make 250 mL of solution. Mixture 2 was obtained by vigorously swirling 90.0 g of fine quartz sand in 250 mL of water until all visible sand was suspended.
The student immediately removes two separate 10.0 mL samples from different locations inside the beaker for each mixture—one sample taken just below the surface and one taken very near the bottom.
(a) For Mixture 1, describe whether the two samples are expected to contain equal, greater, or lesser masses of dissolved solid. Provide reasoning based on macroscopic observations.
(b) For Mixture 2, predict whether the two samples will contain equal, greater, or lesser masses of solid quartz. Explain your answer in terms of macroscopic variability.
(c) Suppose Mixture 2 is allowed to stand undisturbed for 20 min before sampling. Predict how this waiting period will affect the comparison you made in part (b), and justify your prediction.