Question

Assume you recovered 0.291 mL of citral in this experiment. How many grams of lemon grass oil did you begin with if citral comprises 9.44% of the oil?

a) 5.11 g

b) 1.23 g

c) 0.655 g

d) 0.906 g

e) 2.75 g

Answer 1

Given the volume of citral recovered, V = 0.291 mL

Density of citral oil, d = 0.893 g/mL

Hence the mass of citral recovered , m = Vxd = 0.291 mL x (0.893 g/mL) = 0.260 g

Given that lemon grass oil contains 9.44 mass % of citral i.e

9.44 g of citral is present in 100 g of lemon grass oil.

Hence 0.260 g of citral that would be present in the mass of lemon grass oil

= 0.260 g citral x (100 g lemon grass oil / 9.44 g citral)

= 2.75 g lemon grass oil. (e)

Hence (e) is correct