Measurements show that the enthalpy of a mixture of gaseous reactants decreases by 258.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 −51.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. kJIs the reaction exothermic or endothermic?
Question
Measurements show that the enthalpy of a mixture of gaseous reactants decreases by 258.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 −51.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. kJIs the reaction exothermic or endothermic?
Solution
The change in energy of the gas mixture during the reaction can be calculated using the first law of thermodynamics, which states that the change in internal energy (ΔU) of a system is equal to the heat added to the system (q) minus the work done by the system (w). In a chemical reaction at constant pressure, the heat q is equal to the change in enthalpy (ΔH). Therefore, the equation becomes:
ΔU = ΔH - w
Given that ΔH = -258 kJ (the negative sign indicates that heat is released, i.e., the reaction is exothermic) and w = -51 kJ (the negative sign indicates that work is done on the system), we can substitute these values into the equation:
ΔU = -258 kJ - (-51 kJ) = -258 kJ + 51 kJ = -207 kJ
Therefore, the change in energy of the gas mixture during the reaction is -207 kJ. The reaction is exothermic because heat is released (ΔH is negative).
Similar Questions
The enthalpy of a reaction is +270 kJ/mol. What can you determine about the reaction?A.It is exothermic.B.It is nonspontaneous.C.It is endothermic.D.It is spontaneous.
If the heat of reaction, that is the enthalpy change ΔH, for a certain process, is +32 kJ, that process Question 3Select one:a.occurs rapidlyb.is exothermicc.is endothermicd.cannot occure.requires a catalyst
(ii) Show that the heat energy change, Q, in the student’s experiment is about 1100 J.[for the mixture, c = 4.2 J/g/°C][massof1.0 cm 3of mixture = 1.0 g] (3)(iii) The student uses 0.020 mol of potassium hydroxide in his experiment.Calculate the enthalpy change (ΔH) in kJ/mol, for 1.0 mol of potassium hydroxide.Include a sign in your answer.
The enthalpy change upon dissolving 80 grams of ammonium nitrate in water is +25.7 kJ. If 160 grams are dissolved, what will be the change in enthalpy? Group of answer choicesNot enough information to tellIt will be halvedIt will be doubled
An ideal gas has a gas constant R = 0.3 kJ/kg-K and a constant-volume specific heat Cv = 0.7 kJ/kg-K. If the gas has a temperature change of 100 degrees C, what is the change in enthalpy?Question 2Select one:a.30 kJ/kgb.70 kJ/kgc.100 kJ/kgd.insufficient information to determine
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.