Gas pressure

1. Sep 29, 2009

ibysaiyan

1. The problem statement, all variables and given/known data
An Aerosol has a of pressure 250kpa at 17 C.The aerosol is left in the sun and its temp.rises to 27 C.Calculate new pressure in the can if its a 35% increase in the amount of vapour present.

2. Relevant equations
P/T= constant

3. The attempt at a solution
well tbh i am just confused.. do i get T= into kelvin, ok i tried that too...
my first attemp was:
1)(273.15+27)-(17+273.15)=10kelvin
so what i did:10x250x10^3/100= 25kPa
so pressure at 27 is: 250+25=275Kpa
2)
2nd attempt:
PV=nRT
P/T=nr/v
=>P/T= constant
250x10^3/10kelvin=25kpa... which if i add to 250 gives me same answer.. lol i have confused my self badly -(. first i forgot to convert C into Kelvin .
Thanks for the replies in adv.

2. Sep 29, 2009

RoyalCat

Try and work in an ordered way. Always try and structure your work in advance. Write out what you know, and what you're looking for.

And I think you shouldn't work with $$P/T=constant$$
That's just a misleading way of saying that the volume is constant, and I think it can only lead to confusion.

Initial state:

$$P_1 V_1 = nRT_1$$

$$P_1= 250kPa$$

$$V_1=V_2$$ (As long as the can doesn't deform, its total volume remains the same)

$$T_1=(17+273.15) ^o K$$

Final state:

$$P_2 V_2 = nRT_2$$

We are looking for $$P_2$$

$$V_2=V_1$$

$$T_2=(27+273.15) ^o K$$

Now all that you need to do is isolate $$P_2$$ and express it in terms of known quantities.

Last edited: Sep 29, 2009
3. Sep 29, 2009

ibysaiyan

ermm sorry i dont get it , do you mean that i should isolate p2 =nRT2/v2

4. Sep 29, 2009

RoyalCat

Yes...
Now find a way to express $$V_2$$ in terms of known quantities.