Question

A mixture of gaseous reactants is put into a cylinder, where a chemical reaction turns them into gaseous products. The cylinder has a piston that moves in or out, as necessary, to keep a constant pressure on the mixture of 1 atm. The cylinder is also submerged in a large insulated water bath. (See sketch at right.) 1 atm pressure piston .cylinder From previous experiments, this chemical reaction is known to absorb 328. kJ of energy water bath gases The temperature of the water bath is monitored, and it is determined from this data that 363. kJ of heat flows out of the system during the reaction. lo O exothermic Is the reaction exothermic or endothermic? Ar endothermic Oup X Does the temperature of the water bath go up or down? O down O neither O in O out Does the piston move in or out? O neither O does work Does the gas mixture do work, or is work done on it? work is done on it neither How much work is done on (or by) the gas mixture? Be sure your answer has the correct number of significant digits.

Answer 1

1 )reaction is exothermic as the heat flow out of the system

2)The piston will not move down to maintain the 1 atm pressure

3) temperature of water bath will increase as heat flow out of the system

4)The work is done on it

5)Theinternal energy of an ideal gas is proportional to the temperature, so if the temperature is kept fixed the internal energy does not change. The first law, which deals with changes in the internal energy, thus becomes 0 = Q - W, so Q = W. If the system does work, the energy comes from heat flowing into the system from the reservoir; if work is done on the system, heat flows out of the system to the reservoir. So work done by the system is 328 KJ