Question

Consider a hypothetical chemical reaction: A + B ? C + D (In this equation A, B, C and D stand for some unknown chemical formulas.) Here is an energy diagram for the reaction: energy (kJ/mol) 400 300 200 100 0 A + B C + D reaction coordinate Use the energy diagram to answer these questions. What is the heat of reaction? ? ? kJ/mol Is the reaction exothermic or endothermic? ? Exothermic ? Endothermic ? Neither Can you determine the activation energy? ? Yes, it's ? ? kJ/mol ? No. Can you determine the activation energy of the reverse reaction? C + D ? A + B ? Yes, it's ? ? kJ/mol ? No.

          Consider a hypothetical chemical reaction:
A + B ? C + D
(In this equation A, B, C and D stand for some unknown chemical formulas.)
Here is an energy diagram for the reaction:

energy (kJ/mol)
400
300
200
100
0
A + B
C + D
reaction coordinate

Use the energy diagram to answer these questions.
What is the heat of reaction? ? ? kJ/mol
Is the reaction exothermic or endothermic?
? Exothermic
? Endothermic
? Neither
Can you determine the activation energy?
? Yes, it's ? ? kJ/mol
? No.
Can you determine the activation energy of the reverse reaction?
C + D ? A + B
? Yes, it's ? ? kJ/mol
? No.

Show more…

Consider a hypothetical chemical reaction:
A + B ? C + D
(In this equation A, B, C and D stand for some unknown chemical formulas.)
Here is an energy diagram for the reaction:

energy (kJ/mol)
400
300
200
100
0
A + B
C + D
reaction coordinate

Use the energy diagram to answer these questions.
What is the heat of reaction? ? ? kJ/mol
Is the reaction exothermic or endothermic?
? Exothermic
? Endothermic
? Neither
Can you determine the activation energy?
? Yes, it's ? ? kJ/mol
? No.
Can you determine the activation energy of the reverse reaction?
C + D ? A + B
? Yes, it's ? ? kJ/mol
? No.

Added by Melissa P.

Chemistry: Structure and Properties

Nivaldo Tro 2nd Edition

Instant Answer

Solved by Expert Jennifer Hudspeth

01/29/2023

Step 1

Step 1: Identify the starting energy (reactants A + B) from the graph, which is about 50 kJ/mol. Show more…

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Consider a hypothetical chemical reaction: A + B → C + D (In this equation, A, B, C, and D stand for some unknown chemical formulas.) Here is an energy diagram for the reaction: Use the energy diagram to answer these questions: What is the heat of reaction? kJ/mol Is the reaction exothermic or endothermic? Exothermic Endothermic Neither Can you determine the activation energy? Yes, it's kJ/mol No. Can you determine the activation energy of the reverse reaction? C + D → A + B Yes, it's kJ/mol No.

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Transcript

00:03 Hi there.

00:03 In this question, we see a reaction taking place where we start with our reactants, which are a plus b, and energy has to be added to start the reaction.

00:18 That is the activation energy.

00:25 The activation energy is the energy required to start the reaction.

00:37 Once that energy is added, then the reaction proceeds.

00:43 And in this case, we see that our products, c and d are down here.

00:50 So since the y -axis is energy in kilojoules per mole, we see that the products have less energy than the reactants.

01:02 So that means energy was released in this reaction.

01:08 Since the products now have less energy, there must have been energy released.

01:13 So if energy is released, that is an exothermic reaction.

01:18 Exo means out of, so energy has come out of this reaction.

01:23 It is exothermic in that forward direction.

01:26 A plus b yield c plus d is exothermic.

01:30 Okay, can we determine the activation energy? sure we can because we have numbers on this graph.

01:37 The activation energy for the forward reaction is going to be the difference in energy from where they started to the top of that hill.

01:47 And we actually have numbers on the graph...

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