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Anonymous asked in Science & MathematicsChemistry · 2 months ago

Calcium chromate has a limited solubility in water of 1.56 g/100 mL. What is Ksp for CaCrO4?

Answer choices are

a) 9.99e-2

b) 9.96 e-5

c) 1e-4

d) 9.98e-3

1 Answer

  • 2 months ago

    Ksp of CaCrO4 ......

    CaCrO4 <==> Ca^2+ + CrO4^2- ............. Ksp = ???

    (15.6g CaCrO4 / 1L) x (1 mol CaCrO4 / 156.07g CaCrO4) x (1 mol Ca2+ / 1 mol CaCrO4) = 9.9955x10^-2 M Ca^2+

    This also the concentration of CrO4^2- ion.

    Ksp = [Ca^2+][CrO4^2-] = (9.9955x10^-2)^2 = 9.9910x10^-3

    Round to three significant digits: 9.99x10^-3

    Whether the last digit is "8" or "9" is immaterial since it depends on the precision of the molar mass used in the calculations.  The important thing is the order of magnitude (x10^-3).

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