객관식
When 100.0 mL of 0.200 M NaOH is mixed with 50.0 mL of 0.400 M HF in a calorimeter, the temperature increases from 22.50 °C to 24.68 °C. Based on this temperature change, what type of reaction is occurring?
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8. Thermochemistry
Endothermic & Exothermic Reactions
Multiple Choice
C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l), ΔH = -1,370 kJ. For the combustion of ethanol as described above, which of the following statements is true?
A
The enthalpy change would be the same if gaseous water were produced instead of liquid water.
B
The reaction is exothermic.
C
The reaction is endothermic.
D
The reaction absorbs heat from the surroundings.
검증된 단계별 안내1
Identify the type of reaction: The given chemical equation represents the combustion of ethanol, which is a type of exothermic reaction where a substance reacts with oxygen to produce carbon dioxide and water.
Understand the enthalpy change (ΔH): The enthalpy change for the reaction is given as -1,370 kJ. A negative ΔH indicates that the reaction releases heat to the surroundings, which is characteristic of an exothermic reaction.
Consider the states of products: The enthalpy change can vary depending on the physical states of the products. If gaseous water were produced instead of liquid water, the enthalpy change would be different due to the additional energy required to convert liquid water to gaseous water (latent heat of vaporization).
Evaluate the statements: Based on the negative ΔH value, the statement 'The reaction is exothermic' is true. The other statements suggesting the reaction is endothermic or absorbs heat are incorrect.
Conclude the analysis: The key takeaway is that the combustion of ethanol is an exothermic process, releasing heat, as indicated by the negative enthalpy change.
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