Question

1. Ibuprofen, C13H18O2, is the active ingredient in many non-prescription pain relievers.

(a) If the tablets in a bottle contain a total of 13 g of ibuprofen, how many moles of ibuprofen are in the bottle?
Work

N= mass/mr
N=13/206.29g
N=0.0630n



(b) How many atoms of ibuprofen are in the bottle?

Answer 1

a) Moles

n = grams / molar mass

molar mass of C13H18O2:

13*12g/mol + 18*1g/mol + 2*16g/mol = 206 g/mol

n = 13 g / 206 g/mol = 0.063 mol

b) number of atoms = Avogadro number * n = 6.022*10^23 atom/mol * 0.063 mol = 0.379 * 10^23 atoms = 3.8 * 10^22 atoms