How many gallons of water must be added to 10 gallons of 5% hydrogen peroxide solution to get a 1% solution?

Question

I need the answer but I also would like an explanation of how you got that answer so I can figure out other equations like it in the future. I'm taking a chemistry course for work and cannot understand how to get the right answer to problems like this for some reason.

Answer 1

You could use V1C1 = V2C2

V1 = initial volume = 10 gal

C1 = initial concentration = 5%

V2 = final volume = ?

C2 = 1%

Then ...

(10 gal)(5%) = (x gal)(1%)

x = (10)(5) / 1

x = 50 which is the final volume

Since you started with 10 gallons, you'd have to add 40 gallons. That would be the answer.