Question

Measurements show that the enthalpy of a mixture of gaseous reactants decreases by 162. kJ during a certain chemical reaction, which is carried out at a constant pressure. Furthermore, by carefully monitoring the volume change it is determined that -194. kJ of work is done on the mixture during the reaction. Calculate the change in energy of the gas mixture during the reaction. Round your answer to 3 significant digits kI o exothermic O endothermic Is the reaction exothermic or endothermic?

Answer 1

Explanation:

It is given that the energy change is -162 kJ and work done is -194 kJ. As we know that formula for change in enthalpy is as follows.

                           dH = dE + W

where,     dH = change in enthalpy

                dE = change in energy

                W = work done

Therefore, the change in enthalpy will be as follows.

                      dH = dE + W

                            = -162 kJ + (-194 kJ)

                            = -356 kJ

As the negative sign indicates heat is being released. Therefore, the reaction is exothermic in nature.

Thus, we can conclude that the change in energy of the gas mixture during the reaction is -356 kJ.