I have attached a photo of the structure.
You can get better at solving problems like this by practicing a lot!
Answer:
The concentration is 
Explanation:
From the question we are told that
The absorbance is 
The length is 
Generally absorbance is mathematically represented as

where
is the molar absorptivity of FeSCN2 with a value 
and
is the equilibrium concentration of FeSCN2
So

substituting values


Convert temperature to Kelvin
Convert vol to L
Apply Charles law
- V1T_2=V2T_1
- 0.4(400)=498V_2
- 160=498V_2
- V_2=0.32L=320mL
For this reaction to proceed, the following bond breaking should occur:
*one C-H bond
* one Cl-Cl bond
After, the following bond formations should occur:
*one C-Cl bond
*one H-Cl bond
Now, add the bond energies for the respective bond energies which can be found in the attached picture. For bond formations, energy is negative. For bond breaking, energy is positive.
ΔHrxn = (1)(413) + (1)(242) + 1(-328) + 1(-431) =
<em>-104 kJ</em>