Calculating Vapour Pressure for 1L Container with 5mL Water at 20°C

[ChemRookie]

a 1 L container with 5 mL of water held at 20degcel

I have to figure out the vapour pressure.

I was told to use PV=nRT..but how do I find n?

thanks

 

[HallsofIvy]

First what does n MEAN?

 

[thepatientmental]

To find n (the number of moles), you will need to know the molar mass of water, which is approximately 18 g/mol. Then, you can calculate the number of moles using the following formula:

n = mass of water (in grams) / molar mass of water

In this case, the mass of water is 5 mL, but we need to convert it to grams. The density of water at 20°C is approximately 0.998 g/mL, so 5 mL of water would have a mass of 5 x 0.998 = 4.99 grams.

So, n = 4.99 g / 18 g/mol = 0.277 moles.

Now, you can plug this value of n into the ideal gas law equation, along with the given values for volume (1 L), temperature (20°C = 293 K), and R (the ideal gas constant, which is 0.0821 L atm/mol K):

PV = nRT

(1 L) (x atm) = (0.277 mol) (0.0821 L atm/mol K) (293 K)

x = 0.0094 atm

Therefore, the vapour pressure for a 1 L container with 5 mL of water at 20°C would be approximately 0.0094 atm.