# Question #fa01b

##### 1 Answer
Nov 27, 2016

The acid is $\text{triprotic}$.

#### Explanation:

$\text{Moles of NaOH}$ $=$ $30.5 \times {10}^{-} 3 L \times 0.108 \cdot m o l \cdot {L}^{-} 1 = 3.29 \cdot m m o l .$

$\text{Moles of acid}$ $=$ $\frac{0.210 \cdot g}{192 \cdot g \cdot m o {l}^{-} 1} = 1.10 \times {10}^{-} 3 \cdot m o l$

So clearly the acid is triprotic.

The only acid I know that fits these properties is citric acid, ${C}_{6} {H}_{8} {O}_{7}$, which is one of the few triacids. I have never titrated this one, but I think you would be hard-pressed to get a phenolpthalein endpoint at the third equivalent.