Final answer:
To find the concentration of Ca2+(aq) in a saturated solution of CaCO3, we use the Ksp of 4.9 × 10−9 to calculate the molar solubility, which is found to be 7.0 × 10−5 M, corresponding to option C.
Step-by-step explanation:
To calculate the concentration of Ca2+(aq) in a saturated solution of CaCO3, we need to use the solubility product constant (Ksp) given as 4.9 × 10−9. When CaCO3 dissolves, it dissociates into Ca2+ and CO32− ions:
CaCO3(s) → Ca2+(aq) + CO32−(aq)
Let the molar solubility of CaCO3 be 's'. At equilibrium, the concentrations of Ca2+ and CO32− will both be 's' since they dissociate in a 1:1 ratio. Therefore, the Ksp expression is:
Ksp = [Ca2+][CO32−] = s × s = s2
Solving for 's', we get:
s = √(Ksp) = √(4.9 × 10−9) = 7.0 × 10−5M
Hence, the concentration of Ca2+(aq) in a saturated solution of CaCO3 is 7.0 × 10−5M, which corresponds to option C.