How many litres of a 90% solution of concentrated acid needs to be mixed with a 75% solution of concentrated acid to get a 30 l solution of 78% concentrated acid? op 1: 24 l op 2: 22.5 l op 3: 6 l op 4: 17.5 l?
Answers
Answer: -
Option 3 : 6 L
Explanation: -
Let the amount of 90% solution of concentrated acid added be A.
Let the amount of 75% solution of concentrated acid added be B.
Since total volume must be 30 L,
A + B = 30 .......equation 1
Amount of acid in A L of 90% concentrated acid = A x
= 0.9 A
Amount of acid in B L of 75% concentrated acid = A x
= 0.75 B
Amount of acid in 30 L of 90% concentrated acid = 30 x
= 23.4
Thus 0.9 A + 0.75 B = 23.4 ....equation 2
By multiplying equation 1 by 0.9 we get
0.9 A + 0.9 B = 27 .....equation 3
Subtracting equation 2 from 3
We get 0.15 B = 3.6
B = = 24
From equation 1
A + B = 30
A = 30 - B
= 30 - 24
= 6
Thus 6 litres of a 90% solution of concentrated acid needs to be mixed with a 75% solution of concentrated acid to get a 30 l solution of 78% concentrated acid.
Answer:
Explanation:if the number is divisible by 16