Which of the following factors affect heat of a reaction?
Correct answer: D. All of these
- A. Temperature
- B. Physical state of reactants and products
- C. Reaction conditions
- D. All of these
Explanation
The temperature at which a reaction occurs significantly affects the heat of reaction. Changes in temperature can make a reaction more exothermic (releases heat) or more endothermic (absorbs heat). For example, at higher temperatures, reactions often become more endothermic. The physical state of reactants and products (solid, liquid, gas) can influence the heat of a reaction. Phase changes (e.g., from solid to liquid or gas) are associated with specific enthalpy changes (ΔH) known as the enthalpy of fusion, vaporization, or sublimation. The physical state can also affect the specific heat capacity and the heat absorbed or released during the reaction. Reaction conditions encompass various factors such as pressure, concentration, and the presence of catalysts, which can have a profound impact on the heat of reaction. Changes in pressure or concentration can alter the reaction's equilibrium and, consequently, the enthalpy change. The presence of a catalyst doesn't change the overall enthalpy change but can influence the reaction rate and potentially the heat flow.
Last updated
About Thermochemistry and Energetics of Chemical Reactions
Thermochemistry measures energy changes in chemical reactions and distinguishes exothermic from endothermic processes. Work covers systems, surroundings and state functions, internal energy, the first law of thermodynamics, enthalpy and Hess's law, including the sign conventions used when heat enters or leaves a system.
Practise Thermochemistry and Energetics of Chemical Reactions
728 free Thermochemistry and Energetics of Chemical Reactions MCQs from Chemistry, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Chemistry questions like this
Chemistry is on 12 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
Related questions
1/2 H2(g) ➞ H(g) ∆H = 218 kJ mol-1.In this reaction, ∆H will be called:
1 Kcal is equal to:
2P(s) 3CI2(g) 2PCI3 ∆H= 151.8 kJ PCl3+ CI2(g) , PCI5(g); ∆H = -32.8 kJFrom the following data, the heat of formation of PCI5 comes out to be :
5 calories are equivalent to _ Joule.
5 mole of an ideal gas expand reversibly from a volume of 8 dm3 to 80 dm3 at a temperature of 27°C. Calculate the change in entropy.