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AP® Chemistry

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Moderate

Common Ion

APCHEM-WSGB4J

Strontium fluoride, ${ SrF }_{ 2 }$, dissolves in water according to the following equation. The solubility product constant for the process at 25ºC is given.

$${ SrF }_{ 2 }(s)\rightleftharpoons { Sr }^{ 2+ }(aq)+2{ F }^{ - }(aq)\qquad \qquad { K }_{ sp }=8\times { 10 }^{ -10 }$$

Suppose you have 1.0 L of a saturated solution at 25ºC.

Which of the following would result if 1 millimole (1 mmol = ${ 10 }^{ -3 }$ mol) of solid sodium fluoride ($NaF$) were added to the system, which was then allowed to come to equilibrium once again?

A

Nothing. Both the system position and ${K}_{sp}$ will remain the same.

B

The system will shift to the right, but the solubility product constant, ${K}_{sp}$, will remain the same.

C

The system will shift to the left, but the solubility product constant, ${K}_{sp}$, will remain the same.

D

The value of $[{Sr}^{2+}]$ will decrease, while $\left[ { SrF }_{ 2 } \right] $ will increase. ${K}_{sp}$ will remain the same.