Science Buddies: "Ask an Expert"

i am trying to help my son (4th grade) with this. we have the experiment part done but need help determining how to do the equation. how do we figure out the ratio of water /salt for each cup? we have to make cards identifying each cup and take pictures to post to the board; but i dont know the formula. thanks for your help.

Hi,

This is a great project for a 4th grader!

I think this is the project you are doing:

https://www.sciencebuddies.org/science- ... p003.shtml

If you followed the instructions, the first cup contains 292 grams of salt in .946 liters of water, or 308 grams/liter, or you could call it 100%, and the rest of the cups are a 1:2 dilution of the previous cup. So the second cup is one-half, or 154 grams per liter, or 50%. The third cup is 77 grams per liter or 25%. Fourth is 38.5 grams per liter or 12.5%. Fifth cup is 19.25 grams per liter or 6.25%.

Let me know if you did a different series of dilutions, or if there are other questions.

Donna hardy

thanks so much that is alot of help. it's exactly the explanation i was looking for. thanks again.