Chemistry
posted by Laura .
How much Fe++ could be present in water containing 1 x 1e02 M HCO3 (bicarbonate) without causing the precipitation of FeCO3 (Ksp=10**(10.7))

What have you been taught about this. CO3^2 must come from k2; therefore, I would write the ionization and k2 expression.
HCO3^ ==> H^+ + CO3^2
k2 is of the order of 10^11. I would plug in 1 x 10^7 for (H^+) and solve for (CO3^2).
Substitute (CO3^2) in Ksp and solve for (Fe^+2)
Check my thinking.