Question

A throat lozenge contains 5.0 mg of menthol, which has the formula c10h20o.

a. how many moles of menthol are in 5.0 mg of menthol?
b. what is the mass in grams of 1.56 moles of menthol?

Answer 1

a)
the molecular formula of menthol is C₁₀H₂₀O
molar mass of menthol is (12x10) + (1x20) + 16 = 156 g/mol
number of moles of menthol in 156 g - 1 mol
In 1 g of menthol number of moles - 1/156
Therefore in 5.0 g of menthol - 1/156 x 5 = 0.032 mol
therefore in 5.0 g of menthol there are 0.032 mol of menthol

b)
Molar mass of menthol - 156 g/mol
1 mol of menthol weighs 156 g
Therefore 1.56 mol of menthol weighs - 156 g/mol x 1.56 mol = 243.36 g