Question

How much of other chemicals must be evaporated from 400 grams of a hand sanitizer that is 24% alcohol to strengthen it to a hand sanitizer that is 30% alcohol? Correct your answer to the nearest whole number.​

Answer 1

80 g

Explanation:

mass of sanitizer = 400 g

percentage of alcohol = 24%

mass of alcohol in the sanitizer = 24% of 400 g = 0.24 x 400 = 96 g

this means that the mass of other chemicals = 400 - 96 = 304 g

If alcohol content is increased to 30% by removing more of the other chemicals, then mass of alcohol will still remain 96 g

this means that 96 g becomes 30% of the resulting hand sanitizer, we write mathematically as

96 g = 30% of y

where y is the new mass of the sanitizer

96 = 0.3y

y = 96/0.3 = 320 g

The remaining mass of other chemicals = 320 - 96 = 224 g

the total mass of other chemical lost is

304 - 224 = 80 g