Thermal Expansion of Gas - am I on the right track?

[Quelsita]

Question:
One mole of an ideal gas with cv=2.5R, initially at 0.0degC, is heated at constant pressure. How much heat is needed to double its volume?

Solution:

Know:
n=1
T₀=273.15K
c_v=2.5R
\DeltaP=0
V_f=2V₀

H=U +PV
and thus, Q= \DeltaH
Q=nc_v\DeltaT

We can rearrange to find
\DeltaH=\DeltaU +P(2V₀-V₀) -> since V_f=2V₀

My question is, what do I do with the internal energy? and how can I find the pressure with the given information if I also don't know the final temp?

 

[Mapes]

Hint: it's an ideal gas.

 

[Quelsita]

Well, for an ideal gas PV=nRT.
And since P is constant, can I say that:

P₀ = (nRT₀)/V₀
is the same as
P= (nRT₀)/V₀

so , P= [(273.15K)(nR)]/V₀

 

[Mapes]

What's the final temperature?

 

[Quelsita]

Honestly, I'm kinda stuck here. It feels to me like with the information I have that I'm just going in circles using one equation to solve another one.
I don't think this question should even be this confusing...

 

[Mapes]

Use the ideal gas law to find the final temperature when the volume is doubled at constant pressure.