Why these answers are so?
1- For this reaction 2H2 + O2 = 2H2O
a- dela H=delta Hf
b-delta Hc= delta Hf
c- delta H= delta Hc
d- delta S= delta H
and the answer is b , but how and why?
2- For this reaction 2S + 3O2 = 2SO3 + 792 kJ
which of the following isn't correct
a- delta Hc of S = delta Hf of SO3
b- delta H # delta Hf of SO3
c- The reaction is exothermic
d- delta H = delta Hc of S
and the answer is d , how?
3- Whic of the following about this reaction is correct
CO + 1/2 O2 = CO2
a- delta Hf of CO2 = delta H
b- delta H = delta Hc of CO
c- delta Hf of CO2 = delta Hc of CO
d- the heat of reaction and the entropy is equal
and the answer is b , how and why?
Please help me, thank you a lot
To understand why the given answers are correct, we need to understand the concepts involved in each question.
1. For the reaction 2H2 + O2 = 2H2O:
a. delta H = delta Hf: This statement is incorrect because delta H represents the enthalpy change of the reaction, while delta Hf represents the standard enthalpy of formation of a substance.
b. delta Hc = delta Hf: This statement is correct because delta Hc represents the standard enthalpy of combustion, which is equal to the standard enthalpy of formation for the products minus the standard enthalpy of formation for the reactants.
c. delta H = delta Hc: This statement is incorrect because delta H represents the overall enthalpy change of the reaction, including any energy transferred as heat or work, while delta Hc only considers the enthalpy change due to combustion.
d. delta S = delta H: This statement is incorrect because delta S represents the entropy change of the reaction, not the enthalpy change.
Therefore, the correct answer is b, delta Hc = delta Hf.
2. For the reaction 2S + 3O2 = 2SO3 + 792 kJ:
a. delta Hc of S = delta Hf of SO3: This statement is correct because delta Hc represents the standard enthalpy of combustion for S, and delta Hf represents the standard enthalpy of formation for SO3.
b. delta H # delta Hf of SO3: The symbol '#' is not commonly used in this context, but if it represents 'not equal', then this statement is correct because delta H, the overall enthalpy change, is not equal to the standard enthalpy of formation of SO3.
c. The reaction is exothermic: This statement is correct because the reaction releases 792 kJ of energy, indicating an exothermic process.
d. delta H = delta Hc of S: This statement is incorrect because delta H represents the overall enthalpy change of the reaction, while delta Hc only considers the enthalpy change due to combustion.
Therefore, the correct answer is d, delta H ≠ delta Hc of S.
3. For the reaction CO + 1/2 O2 = CO2:
a. delta Hf of CO2 = delta H: This statement is incorrect because delta H represents the overall enthalpy change of the reaction, while delta Hf represents the standard enthalpy of formation of CO2.
b. delta H = delta Hc of CO: This statement is correct because delta H represents the overall enthalpy change of the reaction, which is equal to the standard enthalpy of combustion for CO.
c. delta Hf of CO2 = delta Hc of CO: This statement is incorrect because delta Hf represents the standard enthalpy of formation for CO2, while delta Hc represents the standard enthalpy of combustion for CO.
d. The heat of reaction and the entropy are equal: This statement is incorrect because the heat of reaction (delta H) and entropy (delta S) are different properties and cannot be equal.
Therefore, the correct answer is b, delta H = delta Hc of CO.
I hope this explanation helps you understand why each answer is correct or incorrect. If you have any further questions, feel free to ask!