In: Chemistry
What is the concentration of Ca2+ in ppm (mg/L) in cave water saturated with calcite (calcium carbonate, Ksp = 4.7 × 10-9)?
Answer:2.7
Ksp = 4.7 x 10^-9
CaCO3 ------------------------> Ca+2 + CO3-2
Ksp = [Ca+2][CO3-2]
4.7 x 10^-9 = S^2
S = 6.86 x 10^-5 M
molarity of Ca+2 = 6.86 x 10^-5 M
ppm = mg / L
molarity of Ca+2 = 6.86 x 10^-5 mol / L
= ( 6.86 x 10^-5 mol / L ) x ( 40 g / mol )
= 2.7 x 10^-3 g / L
= 2.7 mg / L
= 2.7 ppm ------------------------> answer