Grade 10 and 11 Extra Concentration Questions (& solutions)

1. Brine is a solution of sodium chloride (NaCl) at 18% m/V, which is used to preserve certain foods. To prepare 250 mL of brine, how much salt must be dissolved?

Problem-solving steps	Application
1. Determine what you are looking for.	The mass of salt needed to prepare 250 mL of brine at 18% m/V
2. Determine the different variables and their respective values.	C = 18% m/V V = 250 mL m = ? g
3 C = . Choose the appropriate formula.	m V
4 = . Replace each variable by its value and isolate the unknown variable.	18 g ? g 100 mL 250 mL Therefore m = 45 g
5. Check your solution and answer the problem question.	The amount of salt needed to prepare 250 mL of brine at 18% m/V is 45 g.