Question 14 of 28intermediate🔧 ApplyNumerical5 marks
Solve the following problems:
(i)
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
Mass percentage of sugar = 15%, Mass percentage of all-purpose flour = 84%, Mass percentage of sodium hydrogencarbonate = 1%
(ii)
A brass alloy contains 70% copper by mass. Calculate the quantities of copper and zinc present in 120 g of brass.
Answer
Mass of copper = 84 g, Mass of zinc = 36 g
Explanation
For part (i), since all components are solids, mass percentage is the most appropriate method to express concentration. For part (ii), brass is an alloy of copper and zinc, so the remaining percentage by mass is zinc.