Question

Equilibrium constants at 25 ?C are listed in the table below.

Substance	Kc	Value of Kc
CaCO3	Ksp	4.5�10?9
H2CO3	Ka1	4.3�10?7
	Ka2	5.6�10?11

What is the molar solubility of marble (i.e., [Ca2+] in a saturated solution) in normal rainwater, for which pH=5.60?

Express your answer to two significant figures and include the appropriate units.