# What is the oxidation number of chromium in K_2Cr_2O_7?

May 24, 2017

We has $C r \left(V I +\right)$........

#### Explanation:

The ion is $C {r}_{2} {O}_{7}^{2 -}$. The sum of the oxidation numbers of the individual elements must equal the charge on the ion. And thus $2 \times C {r}_{\text{oxidation number"+7xxO_"oxidation number}} + = - 2$.

The oxidation number of oxygen in its compounds is usually $- I I$, and it is here..........

So $C {r}_{\text{oxidation number}} = \frac{- 2 + 14}{2} = + 6$, i.e. $C {r}^{V I +}$.