The heat capacity at constant pressure of hydrogen cyanide is given by the expression C p [ J / ( mol ⋅ ° C ) ] = 35.3 + 0.0291 T ( ° C ) Cp[J/(mol·°C)]=35.3+0.0291T(°C) Write an expression for the heat capacity at constant volume for HCN, assuming ideal-gas behavior. Calculate Δ ˆ H ΔHˆ(J/mol) for the constant-pressure process HCN ( v , 25 ° C , 0.80 atm ) → HCN ( v , 200 ° C , 0.80 atm ) HCN(v,25°C,0.80atm)→HCN(v,200°C,0.8 0atm) Calculate Δ ˆ U ΔUˆ(J/mol) for the constant-volume process HCN ( v , 25 ° C , 50 m 3 / kmol ) → HCN ( v , 200 ° C , 50 m 3 / kmol ) HCN(v,25°C,50m3/kmol)→HCN(v,200°C,5 0m3/kmol) If the process of Part (b) were carried out in such a way that the initial and final pressures were each 0.80 atm but the pressure varied during the heating, the value of Δ ˆ H ΔHˆ would still be what you calculated assuming a constant pressure. Why is this so?