# Homework Help: Correcting for room temperature and atmospheric pressure

1. Aug 13, 2007

### iyun

1. I would like to convert 1 milligram of water to mililitres at room temperature and atmospheric pressure
I know that they are equivalent at3.93 celcius and an air pressure of 1013.25kPa

2. Relevant equations

1mg=1ml at 3.93 celcius and 1013 kPa

3. The attempt at a solution

unsure
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Aug 13, 2007

### rootX

ever heard of this formula:
PV=nRT?

use it!

3. Aug 13, 2007

### rootX

oops... that was for gases lol

there might be some for liquids

try assuming that there's a linear relationship ...
so T1/something = T2/something

4. Aug 13, 2007

### hage567

Look up a density table for water.

5. Aug 13, 2007

### iyun

Im unclear on T1/something=T2/something
Theres just one temperature here -water at room temperature
thanks

6. Aug 13, 2007

### mgb_phys

You need a table of the density of water at different temperatures, the pressure is only going to have a very small effect.
There is no law for this as such it is an experimental measurement.

7. Aug 14, 2007

### iyun

how does density play into the equation?

8. Aug 14, 2007

### mgb_phys

The density of water chnages with temperature in a rather unusual way.
The maximum density is at just under 4degC, hotter than that water expands slightly so your 1mg of water will take up slightly more than 1ml of volume at room temperature.
As I said there isn't a law predicting this although there are probably equations which are fits to the experimental data. It certainly isn't linear.

9. Aug 14, 2007