Finding water and glycol percentages from mixture density and temperature

[2slowtogofast]

Homework Statement

I know the density of a mixture of water and glycol. I will call that dmix. I need to find the percentage of water and the percentage of glycol in the mixture. The only other thing I know is the temp.

Homework Equations

d=m/v

The Attempt at a Solution

What am unsure of is the following true

Let x = %glycol
Let 1-x = %water

dmix = (x)dglycol + (1-x)dwater

 

[LawrenceC]

Homework Statement

I know the density of a mixture of water and glycol. I will call that dmix. I need to find the percentage of water and the percentage of glycol in the mixture. The only other thing I know is the temp.

Homework Equations

d=m/v

The Attempt at a Solution

What am unsure of is the following true

Let x = %glycol
Let 1-x = %water

dmix = (x)dglycol + (1-x)dwater

Yes, it's true. Since you have the temperature of the mixture, you can look up the densities of each component at the appropriate temperature. Then proceed.

 

[2slowtogofast]

good. Thanks

 

[Borek]

It is NOT true. Volumes are not additive.

For some substances - ethylene glycol included - it works quite good, but it doesn't in general. SO each time you should check if the density vs composition curve is linear - or not.

 

[2slowtogofast]

Ok I though it might not be true. So is there another way this calc can be done with the given info?

 

[Borek]

Density table is the only sure way to go. That's how my works. Unfortunately, density table for ethylene glycol that is built into the program is limited to 60% w/w. It can be easily extended if you can find a better density table.