gas law

[151AND8TH]

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what is the final pressure of a gas that expands from 2.0L at 10*C to 20.0L at 100*C, if its pressure was initially 6.0 atm?

I know that we are solving P2 in a P1V1T1=P2V2T2 -- the temperature is what throws me off. I thought T2 would be (273+100) which would mean:
P2=[(273+10)*6*2]/[(273+100)(20)]

P2=.445 atm

the real answer is

P2=[(273+100)(6*2]/[((273+10)*)(20)]
0.79 atm

and its because of the temperature switch -- so my question is why is 100*C is not considered T2?

 

[joh020340]

your equation is wrong, it is P1V1/T1 = P2V2/T2

 

[alanan84]

Remember the equation is PV=nRT. Since you need T you divide it out and get it on the other side, PV/T=nR. The n and R are constants so they fall out giving you P1V1/T1=P2V2/T2 like the above post says.

 

[dentalplan]

What practice book was this from?

for anyone: On the real DAT, if we get this kind of question, will we be able to have something to write on? I know we don't get a calculator, but will the real DAT ask these types of numbers, and if so, can we write it down to visualize the equation on paper? Are there actually some centers that dont give you anything to write on?

thanks

 

[151AND8TH]

your equation is wrong, it is P1V1/T1 = P2V2/T2

so using your equation what is the answer? because the problem asked for P2

 

[joh020340]

he already wrote the correct answer. from my equation you can use simple algebra to rearrange it to solve for P2 and plug and chug.

 

[klutzy1987]

The final formula would then be
(P1*V1*T2)/(T1*V2)=P2