IMAT 2013 Chemistry

Hi, I still don’t understand number 2, I remember the shorter bond, the stronger its bond. But this number 2 is true, but C=C is shorter than C-C so it must be stronger than C-C. I still don’t know why? Can anyone help me to explain more of this? I really appreciate you. Thank you very much!

Let’s analyze each answer options to see which ones are correct or wrong:
1). True: the more bonds the shorter the length. so, it will increase from carbon carbon triple bonds to C-C(carbon carbon single bond).

2). True: 2 bonds are stronger than 1 but by less than 2 times the strength why it happens because the second shared electron pair does not have as favorable geometry for bonding as does the first pair also Energy required to break double bond is 614 J while in breaking single bond is 349 J(we don’t need to know this), thus the energy to break double bond is more than single bond but less that twice.

3). True: One bond represents 2 shared electrons, so 3 bonds represents 6 electrons.
Hope it helps:)


Hi, first of all thank for helping me. So after reading your explanation, I understand this way, correct me if I’m wrong. Thanks!
So C= C bond has sigma + pi, so it easier to be broken => its strength is less than twice the strength of C-C bond, right?
In other hands, C=C has sigma + pi so it is stronger than C-C bond, right?
Hope you can correct and explain for me if I wrong. Thank you so much!!!

C=C is stronger than C-C what actually is confusing you is the wording of the question.
Let’s assume that the amount of energy needed to break C-C is 5J so, according to answer option 2 energy required for breaking C=C will be less than twice of what’s required for C-C so it will be less than 10J maybe 9 or 8 we don’t have to worry about the numerical value it’s experiment based. so, this is what meant by C=C being stronger than C-C.
Remember as we increase the carbon carbon bonds so does it’s strength increases.
Does it help?

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Ah okay I got it, thank you so much!!! Have a great day!

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