Part (c): Calculate the concentration of the citrate ion, C6H5O73-, in the 0.10 M solution of citric acid.

Here's how to calculate the concentration of the citrate ion for part (c).

Part (c): Calculate the concentration of the citrate ion, $C_6H_5O_7^{3-}$, in the 0.10 M solution of citric acid.

We'll use the $K_a$ values and the $[H^+]$ concentration determined in part (b).
The relevant dissociation constants are:
$K_{a1} = 7.4 \times 10^{-4}$
$K_{a2} = 1.7 \times 10^{-5}$
$K_{a3} = 4.0 \times 10^{-6}$

From part (b), the equilibrium concentration of $H^+$ from