Math Question (re: Specific Gravity)

[rlpardue]

Hi all,

I have a 35g container full of water that's over-salted and need to dilute it. Just wondering if there is a quick math method to do this precisely.

There's 35g of 40ppt water. How many more gallons of RODI water do I need to add to get it down to 35ppt? (And how do I do this math next time?)

Thanks!

 

[NHATRANG]

Add 5g. I think you can use dilution equation to solve: C1xV1=C2xV2
C=concentration
V= volume
C1=40ppt
V1=35g
C2=35ppt
V2=X
40x35=35X
1400=35X
X=40
Now compare V2 TO V1
35g at 40ppt
40g at 35ppt
larger V-smaller V 40-35=5
you need to add 5g to dilute.

 

[bertoni]

That should be about right.

 

[rlpardue]

Thanks!

 

[r-balljunkie]

uugh, repressed memories from college coming back.....