Chemistry problem???????????

Question

The heat of neutralisation of HCl by NaOH is -55.9 KJ/mol.If the heat of neutralisation of HCN by NaOH is -12.1 KJ/mol.The energy of dissociation of HCN is------

Answer 1

Reaction is as follows: HCN(aq) + NaOH(aq) ---> H2O(l) + NaCN(aq)

You need to look at bond energies of each atoms' bond to another atom for each compound present here and subtract the sum of the energies of the bonds broken from the sum of the energies of bonds formed. The answer should equal -21.1 KJ/mol.

Broken:

(H-C bond = 411kJ/mol + C-N bond = 305kJ/mol + Na-O bond = 256.1 kJ/mol + Na-H bond = 185.69kJ/mol ) - (2 x H-O bond = 918kJ/mol + NaCN bond = 434.4 kJ/mol) ====>

(1157.79kJ/mol)-(1352.4kJ/mol)

= -195. kJ/mol

Here is an answer but I believe my sources were inaccurate. This is the basic concept of how to solve the problem though.

Answer 2

that is a very tricky question

Answer 3

Well, the structure of HCN is like: H-C-N. You have H-C bond which is 411kJ/mol + C-N bond which is 305kJ/mol. Add them up and it takes 716kJ/mol to break HCN up. If that is what you are asking.