1. Tardigrade
  2. Question
  3. Chemistry
  4. The polymerisation of ethylene to linear polyethylene is represented by the reaction, .n[ CH 2= CH 2] longrightarrow -[ CH 2- CH 2]n- where, n has large integral value. Given that the average enthalpies of bond dissociation for C = C and C - C at 298 K are +590 and +311 kJ / mol respectively, calculate the enthalpy of polymerization per mole of ethylene at 298 K.

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Q. The polymerisation of ethylene to linear polyethylene is represented by the reaction,
$\left.n\left[ CH _{2}= CH _{2}\right] \longrightarrow -[ CH _{2}- CH _{2}\right]_{n}-$
where, $n$ has large integral value. Given that the average enthalpies of bond dissociation for $C = C$ and $C - C$ at $298 \,K$ are $+590$ and $+311\, kJ / mol$ respectively, calculate the enthalpy of polymerization per mole of ethylene at $298\, K$.

IIT JEEIIT JEE 1994Thermodynamics

Solution:

Per mole of ethylene polymerized, one $C = C$ bond is broken and two $C - C$ bonds are formed.
$\Delta H^{\circ}$ (Polym. $)=590-2 \times 311$
$=-32 \,kJ / mol$