What is the new absolute pressure? p2?

Question

A gas sample enclosed in a rigid metal container at room temperature (20) degrees celsius has an absolute pressure (p1). The container is immersed in hot water until it warms to 40 degrees celsius.

Answer 1

Use the ideal gas law here.

pV = nRT.

Here V, n and R are constant.

Hence p/T is constant

If T increases, then P must increase also.

p1/T1 = p2/T2

P2 = p1*(T2/T1)

But you must use T in Kelvin. ie T1 = 293 K and T2 = 313 K

Answer 2

(p1)(V)=nR(20+273.15)
(p2)(V)=nR(40+273.15)
from the first one, by isolating nR/V, which is common to both equations, you get
p1/(20+273.15)=nR/V
and
p2=nR/V (40+273.15)
substitute, and get
p2=p1(40+273.15)/(20+273.15)
or
p2 = 1.068 p1