Q2. The specific internal energy of formaldehyde (HCHO) vapor at 1 atm and moderate temperatures is given by the formula (J/mol) = 25.96T +0.0213412 where T is in C. (a) Calculate the specific internal energies of formaldehyde vapor at 0C and 100C. What reference temperature was used to generate the given expression for U? (b) The value of calculated for 100C is not the true value of the specific internal energy of formaldehyde vapor at this condition. Why not? (Hint: Refer back to Section 7.5a.) Briefly state the physical significance of the calculated quantity. (c) Use the closed system energy balance equation to calculate the heat (I) required to raise the temperature of 3.0 mol HCHO at constant volume from 0C to 100C. List all of your assump- tions. (d) From the definition of heat capacity at constant volume, derive a formula for C.(T)[J/mol-C). Then use this formula and Equation 8.3-6 to calculate the heat (J) required to raise the temper- ature of 3.0 mol of HCHO(v) at constant volume from 0C to 100C [You should get the same result you got in part (c).]