Question

15&16

QUESTION 15 0.6M NaCl and 0.6M CaCl2 solutions are not isotonic. True False QUESTION 16 1 points (Ext. Connecting ideas. The chemical equation for the dissolution of CaCO3 in water, where Ca2+ and CO32- represents the dissolved form, is: CaCO3 = 0,2+ +0032 The equilibrium constant for this reaction is 3.36x109 This means that a significant amount of calcium carbonate will dissolve in water. True False

Answer 1

15.

True

NaCl dissociates to two particles (Na⁺ and Cl^-) in water, whereas, CaCl₂ dissociates to 3 particles (Ca²⁺ and 2 Cl^-) in water. Thus, the effective concentration (osmol) of 0.6 M NaCl is less than the effective concentration of 0.6 M CaCl₂. Hence, the solutions are not isotonic.

16.

False

Equilibrium constant, K = [Ca²⁺][CO₃^2-]/[CaCO₃]

If K >1 than the equilibrium favors in the forward direction.

But here K = 3.36 x 10^-9 which is <<1. Hence, the equilibrium favors in the reverse direction. This means CaCO₃ is sparingly soluble in water.