how much water should be added to 4 gallons of a 5% herbicide solution to dilute it to a 3.2% herbicide solution?

Question

help I need the answer.

Answer 1

This is a very tricky question

 

the concentration at hand is 5% = 5g in 100g

you want the concentration to be 3.2% which is 3.2g in 100g (water)

so we must first find the increase in water to get to the lower concentration

 

5g/3.2g = 1.56

 

this means you would need 156g (ml) of water for those 5% to change into 3.2%

 

NOW, we are not talking about 100ml, but 4 gallons. 

 

The same ratio applies: 4 gallons * 1.56 = 6.24 gallons

 

Finally  --> subtract 4 gallons (initial volume) from 6.24 (calculated volume) = 2.24 gallons.

 

You will need to add 2.24 Gallons of water to dilute the 5% solution into a 3.2% solution