Question

3. Calculate the mass of each of the following: (report mass in grams)

a) 1.6 x 1022 molecules of aspirin (C9H8O4)

b) 0.52 mol SO3

c) 22.5 mol KMnO4

d) 100 kmol FeO

Answer 1

the molecular mass of aspirin is 180g/mol ( i calculated it just now)
1 mole of aspirin contains 6.02 * 10^23 molecules
1 mole of aspirin = 180g of aspirin
180 moles of aspirin contains 6.02 * 10^23 moleculs
if 6.02 * 10^23 molecules weighs 180g
then 1.6 * 10^22 moleucules will weigh (1.66 * 10^22 * 180)/6.02 * 10^23
= 4.960 g

b) Molar mass of SO3 = 80.066 g/mol

0.052 mol of SO3 = 0.052 * 80.066 g/mol = 4.163g

c) Molar mass of KMnO4= 158.034 g/mol

22.5 mol of KMnO4 = 22.5 * 158.034 g/mol = 3555.765 g

d) Molar mass of FeO= 71.844 g/mol

100 * 10^3 mol of FeO= 71.844 g/mol * 100 * 10^3 mol= 7184400 g