Question

Use the four-step procedure to solve the following problem. Brine is a solution of salt and water. If a tub contains 50 pounds of 5% solution of brine, how much water (to the nearest tenth lb.) must evaporate to change it to an 8% solution?

Answer 1

18.3 pounds of water must evaporate to make it 8% solution

Explanation:

Brine is a solution containing water & salt

Weight of brine solution = 50 pounds

amount of salts = 5% of 50 pounds = (5 ÷ 100) × 50 = 2.5 pounds.

Amount of water = 50 - 2.5 = 47.5 pounds

The new solution is to be made 8%, which indicates that 2.5 pounds of salt is going to be equivalent to 8% of the new salt and some amount of water has to be evaporated for the amount of salt to increase

Using direct relation expression

8% of the solution equivalent to 2.5 pounds of salt

100% will be equivalent to X pounds of solution

Upon cross multiplication,

X = (100 × 2.5) ÷ (8) = 31.25 pounds of solution

There amount of water that must evaporate is difference between weight of initial solution & final solution

Amount of water to be evaporated = 50 - 31.25 = 18.25 pounds ∞ 18.3 lbs