# Question #3015d

Nov 11, 2015

$C {u}_{2} O$

#### Explanation:

First, we need to find the amount in moles of each substance. WE have the mass for each so we use the formula:

$n = \frac{m}{M}$

Where $n$ is the amount of the substance in moles, $m$ is the mass of the substance, and $M$ is the molar mass or molecular mass of the substance, which we can find by looking at the atomic mass on a periodic table so:

$n \left(\text{Cu}\right) = \frac{8.882 g}{63.546 g m o {l}^{-} 1} = 0.139772763 m o l$

and:

$n \left(O\right) = \frac{10 g - 8.882 g}{15.9994 g m o {l}^{-} 1} = 0.06987762041 m o l$

Now we find the ratio of the copper and oxygen by dividing both values by the lowest value:

$C u : O = \frac{0.139772763 m o l}{0.06987762041 m o l} : \frac{0.06987762041 m o l}{0.06987762041 m o l}$

$= 1.999535219 : 1$

The value of 1.999535219 can be rounded to 4 significant figures to get a ratio of $2 : 1$, as the figures in the question are given to 4 s.f.

From this ratio we can get the empirical formula of $C {u}_{2} O$