When a sample of solid is dissolved completely in water

CHEMISTRY · Single correct · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures

Problem

When a sample of solid K2SO4\text{K}_2\text{SO}_4 is dissolved completely in water, which of the following particulate-level descriptions most accurately represents the species present in the solution? (a) Equal numbers of K+\text{K}^+ and SO42−\text{SO}_4^{2-} ions are shown, each surrounded by water molecules. (b) Separate K+\text{K}^+ ions and SO42−\text{SO}_4^{2-} ions, with twice as many K+\text{K}^+ as SO42−\text{SO}_4^{2-}, all dispersed among water molecules. (c) Pairs of K2SO4\text{K}_2\text{SO}_4 units remain associated as neutral clusters surrounded by water molecules, with no individual ions shown. (d) Individual K2+\text{K}^{2+} ions and SO44−\text{SO}_4^{4-} ions are present in a 1:1 ratio, each solvated by water molecules.

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