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, \(\mathrm{Cu}_{x} \mathrm{O}_{y},\) we find that
a sample weighing \(0.5424 \mathrm{g}\) contains \(0.4831 \mathrm{g}
\mathrm{Cu}\).
a. How many moles of Cu are there in the sample? $$\text { (No. moles
}\left.=\frac{\text { mass } \mathrm{Cu}}{\text { molar mass }
\mathrm{Cu}}\right)$$ ________ 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 \(\mathrm{O}\) ) 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? _______ \(g\)
