A student accidentally poured 2 liters of 20% acid solution into a container having 10 liters of 15% acid solution. What is the concentration of the new solution?
The concentration of the new solution is 15.83 %.
A 15 % concentration means
So the volume of acid in 10 L of solution is
So you have
And in 2 L of 20 % acid,
After mixing, the new solution contains 1.5 L + 0.4 L = 1.9 L of acid and has a total volume of 2 L + 10 L = 12 L.
The new concentration is 15.83 %.