How many litres of an 80% concentrated acid solution should be mixed with a 40…
2025
How many litres of an 80% concentrated acid solution should be mixed with a 40 L solution of 85% concentrated acid to get a final solution of 82% concentration?
- A.
30
- B.
60
- C.
16
- D.
27
Attempted by 595 students.
Show answer & explanation
Correct answer: B
Let x be the number of litres of the 80% acid solution to add.
Total acid from both solutions = 0.8x + 0.85*40. Total volume after mixing = x + 40. Set up the equation for 82% final concentration:
0.8x + 0.85*40 = 0.82*(x + 40)
Expand both sides: 0.8x + 34 = 0.82x + 32.8
Bring x terms to one side: 34 - 32.8 = 0.82x - 0.8x = 0.02x
So 1.2 = 0.02x, hence x = 1.2 / 0.02 = 60
Check: total acid = 0.8*60 + 0.85*40 = 48 + 34 = 82. Total volume = 60 + 40 = 100. Concentration = 82/100 = 82%.
Answer: 60 litres of the 80% acid solution should be mixed with the 40 L of 85% solution to obtain an 82% solution.