Ea for the reverse reaction

[EpicDentist]

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"What is the Ea for the reverse reaction of Step 1?"

The answer says +60? Wouldn't it be negative 60 since the reverse would be exothermic?

Edit: Just realized wrong forum...sorry...but can someone help anyway?

 

[BABSstudent]

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But the reason why it is positive is you are going from 40 to 100, inputting energy. The delta G is negative and is exothermic, but that doesn't change Ea. Ea will always (I think) be positive.

 

[kpcrew]

Tell me why it's exothermic.

 

[wolfie77]

"What is the Ea for the reverse reaction of Step 1?"

The answer says +60? Wouldn't it be negative 60 since the reverse would be exothermic?

Edit: Just realized wrong forum...sorry...but can someone help anyway?

I think activation energy is always positive.

 

[MangoPlant]

delta Energy = Energy products - Energy reactants. In this case the "product" is the peak (100), and the reactant is the area between the two peaks, 40.

delta Energy = 100 - 40 = 60

 

[lobo.solo]

The rev. is endothermic that's why is +60.

 

[Sephiroth]

Since this hasn't been locked yet and the answers and ppl haven't given a complete answer which may just confuse you more...

Ea is the activation energy, not the net energy of the reaction. step one take you from the far left (at 20 kJ) over the first hump to the valley at 40 kJ. To reverse that, the activation requires you to get from the start (the valley at 40 kJ) to the top of the peak (100kJ). Thats a 60 kJ energy input - which is your activation energy. Even though at the end a net of 20kJ will be released (exothermic as you said), that isn't relevant to the question.

 

[sliceofbread136]

Didn't we learn this in like middle school?

 

[911 Turbo]

Since this hasn't been locked yet and the answers and ppl haven't given a complete answer which may just confuse you more...

Ea is the activation energy, not the net energy of the reaction. step one take you from the far left (at 20 kJ) over the first hump to the valley at 40 kJ. To reverse that, the activation requires you to get from the start (the valley at 40 kJ) to the top of the peak (100kJ). Thats a 60 kJ energy input - which is your activation energy. Even though at the end a net of 20kJ will be released (exothermic as you said), that isn't relevant to the question.

Yep 👍