If one can find the ratio of the number of moles of the elements in a compound
to one another, one can find the formula of the compound. In a certain
compound of copper and oxygen, \(\mathrm{Cu}_{x}\) o, we find that a sample
weighing 0.6349 g contains 0.5639 g Cu.
a. How many moles of Cu are there in the sample?
$$\left(\text {No. moles} =\frac{\text { mass Cu }}{\text { molar mass }
\mathrm{Cu}}\right)$$
______________ moles
b. How many grams of O are there in the sample? (The mass of the sample equals
the mass of Cu plus the mass of O.)
______________ g
c. How many moles of O are there in the sample?
______________ moles
d. What is the mole ratio (no. moles Cu/no. moles O) in the sample?
______________ : 1
e. What is the formula of the oxide? (The atom ratio equals the mole ratio,
and is expressed using the smallest integers possible.)
______________
f. What is the molar mass of the copper oxide?
______________ g/mol
