1. A gas bottle with a volume of 0.1 m3 contains 0.4 kg of a gas at a pressure of 7 MN/m2 and a temperature of 150 ºC. For this gas Cp = 10.54 kJ/kg K. Calculate the changes in internal energy when temperature is raised to 500K Given answer: 362 kJ 2. pV=mRT pv=RT mCpdT=dH mCvdT=dU dq-dw=du 3. so i've been struggling with this for a while. i know that du=dq as there is no net work when volume is constant. initially i used p1V1/mT1=R and then i used Cp=R+Cv to find Cv. From there i used the equation mCvdT=dU. however this doesnt give the correct answer. ive been trying a few other ways as well but they havent worked. is there some assumption i can make etc...?