# Calculating molar specific heat capacity - not a monatomic gas

1. Jan 20, 2013

### PhysicsFriend

1. Suppose that 25 J of heat is added to one mole of an ideal gas. The gas expands at a constant pressure of 2.62 x 10^4 pascals while changing its volume rom 4.97 x 10^-4 m^3 to 7.02 x 10^-4 m^3. Calculate C_p and express in Joule / (mole * Celsius)

2. Relevant equations
Q = C_p*n*(delta T)
P(Delta V) = nR(Delta T)

3. Attempt at solution
25 J = C_p (1 mole) (Delta T)

Delta T = .64632 Kelvin
Delta T = -272.35 Celsius

25 J = C_p (1 mole) ( .272.35 Celsius)

C_p = -.0918 J / (mole*Celsius)

4. Question:
I inputted the answer into the online system as +.0918 J / (mole*celsius)
However, it is telling me that I am wrong.

Could there be a negative molar specific heat capacity? That doesn't make too much sense to me because shouldn't the molar specific heat raise the temperature?

Or did I do some stupid mistake with units/wrong equations?

2. Jan 20, 2013

### PhysicsFriend

Never mind.

I see that J/mole*C is the same thing as J/mole*Kelvin
No need for a conversion.