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Question: What would be the correct order of increasing \(C - O\) bond strength of \(CO,CO_3^{2 - },C{O_2}\)? ...

What would be the correct order of increasing C−OC - O bond strength of CO,CO32−,CO2CO,CO_3^{2 - },C{O_2}?
A) CO32−<CO2<COCO_3^{2 - } < C{O_2} < CO
B) CO2<CO32−<COC{O_2} < CO_3^{2 - } < CO
C) CO<CO32−<CO2CO < CO_3^{2 - } < C{O_2}
D) CO<CO2<CO32−CO < C{O_2} < CO_3^{2 - }

Explanation

Solution

As we know that the bond strength is basically the power with which two atoms can be held together with the help of chemicals bonds and bond strength is inversely proportional to the bond order of the molecule and greater the bond order, lesser will be the strength of bond and greater will be the bond energy.

Complete answer:
As we know that bond strength informs us about how strongly the two or more than two atoms are joined with one another with the help of chemical bonds and thus how much energy will be required to break that bond between two atoms.
We also know that the bond dissociation energy is directly proportional to the bond order of the molecule and greater the bond order, greater will be the dissociation energy of bond. Also, typically the bond energy of single bond between carbon-carbon atoms is less than that of double bonds which in turn is less than that of the triple bonds between the two carbon atoms and the bond energy between the single bond of carbon- oxygen atom is less than that of the double and triple bonds between these two atoms.
So, we can first calculate the bond order of all the three given species and then can compare their bond energy and bond strength.
So, the first compound is COCO where we know that carbon and oxygen atoms are held together with the help of triple bonds. So the bond order which is the ratio of the total number of bonds between two atoms to the total resonating forms for COCO will be:
B.O=31=3B.O = \dfrac{3}{1} = 3
Similarly the bond order of CO2C{O_2} can be calculated as we know that carbon and two oxygen are held together with double bonds like O=C=OO = C = O and can have two resonating structures. Hence the bond order will be:
B.O=42=2B.O = \dfrac{4}{2} = 2
Lastly, we have carbonate CO32−CO_3^{2 - } and it is held together by double and single bond and can form three resonating structures, therefore the bond order will be:
B.O=43=1.33B.O = \dfrac{4}{3} = 1.33
Hence from the above explanation we can say that the bond order is decreasing in the order CO>CO2>CO32−CO > C{O_2} > CO_3^{2 - } and we know that bond strength is inversely related to bond order, so the bond strength in increasing order would be CO<CO2<CO32−CO < C{O_2} < CO_3^{2 - }.
Hence, the correct option is (D).

Note: Always remember that bond dissociation energy is directly related to the bond order of the given molecule or compound. As the bond order increases of a given compound, the bond dissociation energy will always increase and if it decreases, the bond dissociation energy will also decrease and reverse is the case with bond strength, with increases in bond order, bond strength decreases and vice versa.