Measurements show that the energy of a mixture of gaseous reactants increases by 188.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 −71.kJ of work is done on the mixture during the reaction.Calculate the change in enthalpy of the gas mixture during the reaction. Round your answer to 3 significant digits.
Question
Measurements show that the energy of a mixture of gaseous reactants increases by 188.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 −71.kJ of work is done on the mixture during the reaction.Calculate the change in enthalpy of the gas mixture during the reaction. Round your answer to 3 significant digits.
Solution
The change in enthalpy (ΔH) of a system at constant pressure is given by the equation:
ΔH = q_p + w
where: q_p is the heat absorbed or released by the system at constant pressure, and w is the work done on the system.
In this case, the energy of the gaseous reactants increases by 188 kJ, which means that the system has absorbed 188 kJ of heat at constant pressure. Therefore, q_p = +188 kJ.
The work done on the system is -71 kJ. Therefore, w = -71 kJ.
Substituting these values into the equation gives:
ΔH = (+188 kJ) + (-71 kJ) = 117 kJ
Therefore, the change in enthalpy of the gas mixture during the reaction is 117 kJ.
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