# How many grams of chromium are needed to react with an excess of CuSO_4 to produce 16.2 g Cu?

Mar 15, 2018

its $8.775 g$

#### Explanation:

Write down the equation for this reaction and balance it

$3 C u S {O}_{4} + 2 C r = 3 C u + C {r}_{2} {\left(S {O}_{4}\right)}_{3}$
Calculate the amount of moles of copper. We have $16 g$, and its molar mass is $64 g$:

$\frac{16}{64} = 0.25$

And thus the mole for chromium will be $0.17$

As the ratio suggests $2 : 3$

Thus $\frac{0.25 \cdot 2}{3} = 0.17$

Use this mole and substitute in the equation $\text{moles"="mass"/"molar mass}$ to calculate the mass which is $0.17 \cdot 52 = 8.775 g$