A nurseryman is preparing an insecticide by mixing a 95% solution with water (0% solution). How much solution and how much water are needed to fill a 100 L tank with 3.8% solution?
You need 4 L of solution and 96 L of water.
The key to solving this problem is understanding that all the solute that exists in the 100-L solution comes from the 95% solution.
This means that you can figure out how much solution you need to mix with water by calculating how much solute you get in the final 100-L sample.
This means that you have
Now use the percent concentration of the 95% solution to figure out how much solution would contain 3.8 L of solute
This means that you need
The volume of water would be