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## Homework Statement

We have 1m

^{3}of Ar gas M=39.948g/mol, pressure=101300Pa, temperature T=298K. We put the energy Q=1000J in that gas. Whats the temperature after we put 10

^{3}J. (c=0.5203x10

^{3})

## Homework Equations

Im not interested in solution. I tried to solve it on two ways using formula for internal energy of ideal gas [tex]\Delta[/tex]U = [tex]\frac{3}{2}[/tex]nR[tex]\Delta[/tex]T and the formula Q = mc[tex]\Delta[/tex]T

However solutions are not the same, why?

## The Attempt at a Solution

pV=nRT => n = pV / RT = 40.89mol

m = Mn = 1633g = 1.633kg

[tex]\Delta[/tex]U = [tex]\frac{3}{2}[/tex]nR[tex]\Delta[/tex]T

thus [tex]\Delta[/tex]T = Q / [tex]\frac{3}{2}[/tex]nR = 1000 / (1.5*40.89*8.314) = 1.961°K

however

Q = mc[tex]\Delta[/tex]T

thus [tex]\Delta[/tex]T = Q / mc = 1000 / (1.633*0.5203*10

^{3}) = 1.177°K

what is wrog please?