The empirical formula of styrene is CH; the molar mass of styrene is 104.14 g/mol. How many H atoms are present in a 7.80 g sample of styrene?

In 7.80 g of styrene, we have 3.60*10²³ atoms of H

Explanation:

Empirical formula of styrene is CH

Molecular formula of styrene is C₈H₈

So, 1 mol of styrene has 8 moles of C and 8 moles of H and 1 mol weighs 104.14 grams. Let's make a rule of three:

104.14 g (1 mol of C₈H₈) have 8 moles of H

Then 7.80 g would have (7.80.8) / 104.14 = 0.599 moles

As we know, 1 mol of anything has NA particles (Avogadro's Number, 6.02*10²³), so 0.599 moles will have (mol. NA) particles

0.599 mol. 6.02*10²³ atoms / 1 mol = 3.60*10²³ atoms