A cylinder contains a mixture of gases under constant atmospheric pressure. The gases undergo a chemical reaction. Upon reacting, the gases absorb 877 J of heat from the surroundings and the surroundings do 0.248 kJ of PV work on the gases. What is the value of AH in joules for this process?

Large helium-filled balloons are used to lift scientific equipment to high altitudes. what is the pressure inside such a balloon if it starts out at sea level with a temperature of 10.0ºc and rises to an altitude where its volume is twenty times the original volume and its temperature is – 50.0ºc ?