Question

Solve the following problem:

A cake recipe uses dry ingredients, namely 75 g of sugar for 420 g of all-purpose flour and 5 g of sodium hydrogencarbonate. Express the concentration of each component in the mixture using an appropriate method.

Answer 1

As this is a mixture of solids, mass by mass percentage (% m/m) is the correct strategy.

Total mass of the mixture = 75 g + 420 g + 5 g = 500 g

Mass by mass percentage of a component 

= `"Mass of the component"/"Total mass of mixture" xx 100`

Mass by mass percentage of sugar

= `75/500 xx 100 = 15%` m/m

Mass by mass percentage of all-purpose flour

= `420/500 xx 100 = 84%` m/m

Mass by mass percentage of sodium hydrogencarbonate

= `5/500 xx 100 = 1%` m/m

Hence, the mixture contains 15 % m/m sugar, 84 % m/m all-purpose flour and 1 % m/m sodium hydrogencarbonate.