Question

The enthalpy change for the reaction of 50 ml of ethylene with 50.0 ml of h2 at 1.5 atm pressure is h = - 0.31 kj. What is u

Answer 1

Relationship in between enthalpy change and internal energy

Explanation:

• From the given data, the required chemical reaction is

$C_2H_4 + H_2 \to C_2H_6$

• Reactants of the mixture combining in the ratio of  1:1

• Thus, 50 ml of ethylene react with 50 ml of $H_2$ to produce 50 ml. of ethane.

        i.e., Volume of ethane = 50 ml

• Volume of reactants = $C_2H_4+H_2$ = 100 ml

• Therefore, Change in volume = 50 ml = 0.05 L

       Pressure = 1.5 atm

       $P \Delta V=1.5 \times 0.05 \\ = 0.075 L atm = 7.5 joules$

• From the first law of thermodynamics,

       $\Delta U = \Delta H + P \Delta V$

               $= -0.31KJ + 7.5J \\= -3025KJ$