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**[SOLVED] Work Done and final temperature of 5 mols of Ideal Gas**

## Homework Statement

Five moles of an ideal monatomic gas with an initial temperature of 129 degrees Celsius expand and, in the process, absorb an amount of heat equal to 1160 Joules and do an amount of work equal to 2020 Joules.

What is the final temperature of the gas?

## Homework Equations

[tex] W = -nR(T_f - T_i) [/tex]

## The Attempt at a Solution

I have used the above formula before, and it worked then but doesn't appear to be working as well now

[tex] 2020 - 1160 = -5*8.31(T_f - 129) [/tex]

[tex] 420 = -41.55(T_f - 129) [/tex]

[tex] -10.1 = T_f - 129 [/tex]

[tex] T_f = -10.1 + 129 [/tex]

This gives me 118.9, which I have entered, and it says that:

*" Not quite. Check through your calculations; you may have made a rounding error or used the wrong number of significant figures. "*

I have tried also 120 as well, with the same response!

I doubt its the formula, because I have used it before? Any Ideas?

TFM