Question

The addition of NaOH to $C{r}^{3+}$ solution produces the precipitate of

• A. $Cr(OH{)}_3$
• B. $Cr{O}_3$
• C. $C{r}_2{O}_3{\left(H_{2}O\right)}_n$
• D. $C{r}_2{O}_3$

Answer 1

Answer: (C)

$Cr(OH{)}_3$ is not precipitated, but the hydrated oxide, $C{r}_2{O}_3{\left(H_{2}O\right)}_n$ is precipitated

$C{r}^{3+}+3O{H}^{-}\to Cr(OH{)}_3\to C{r}_2{O}_3{\left(H_{2}O\right)}_n$