17) What is the (Delta Hrxn) for the reaction?
a) -200.5 kJ
b) -2219 kJ
c) -3182.5 kJ
d) -2389.5 kJ
e) -2267.7 kJ
18) Based on the (Delta Hrxn) for the reaction, we can argue that:
a) The reaction is exothermic
b) The reaction is endothermic
c) The system released a lot of energy and the surroundings did not absorb it
d) The surroundings gave a little energy to the system for the reaction to occur
e) None of the above
19) Hess’s Law is interesting because it allows you to determine the (Delta Hxrn) for a reaction using the (Delta H) of others. This is possible because:
a) The (Delta Hxrn) is only dependent on the initial and final states.
b) The (Delta Hxrn) is a function of the step. So I can use the others (Delta H) of the other reactions
c) (Delta Hxrn) is a function of the state.
d) Statements a and c are correct.
e) Statements a and b are correct
20) In the exercise you just did, to use Equation 3 in determining the (Delta Hxrn), I have to:
a) Leave it the same and multiply the (Delta H) they give me by 2
b) Invert it and multiply the (Delta H) they give me by 2
c) Invest it and also change the sign of the (Delta H) that they give me
d) I don’t have to do anything.
e) I just have to change the sign of the (Delta H) they give me.
The Correct Answer and Explanation is :
Here are the correct answers:
17) What is the (ΔHrxn) for the reaction?
Answer: e) -2267.7 kJ
18) Based on the (ΔHrxn) for the reaction, we can argue that:
Answer: a) The reaction is exothermic
19) Hess’s Law is interesting because it allows you to determine the (ΔHrxn) for a reaction using the (ΔH) of others. This is possible because:
Answer: d) Statements a and c are correct.
20) In the exercise you just did, to use Equation 3 in determining the (ΔHrxn), I have to:
Answer: c) Invert it and also change the sign of the (ΔH) that they give me.
Explanation:
Question 17:
To determine the enthalpy change (ΔHrxn) for the reaction, we need to apply Hess’s Law, which states that the enthalpy change of a reaction depends only on the initial and final states, not the pathway taken. The correct answer is -2267.7 kJ, meaning the reaction releases this much energy.
Question 18:
Since ΔHrxn is negative, the reaction is exothermic. This means the system releases energy to the surroundings. The only correct answer is (a) The reaction is exothermic.
Question 19:
Hess’s Law states that enthalpy is a state function, meaning that the overall enthalpy change only depends on the initial and final states, not the steps in between. This allows us to determine ΔHrxn using other reactions. The correct answer is d) Statements a and c are correct, since enthalpy depends only on the state, not the steps.
Question 20:
If we use Equation 3 to determine ΔHrxn, we may need to invert it, which means reversing the reaction and changing the sign of ΔH. This follows the principle that if a reaction is flipped, the enthalpy sign must also flip. The correct answer is (c) Invert it and also change the sign of the (ΔH) that they give me.