Question

For steady flow through heat exchanger at approximately atmospheric pressure, what is the final temperature when heat in the amount of 800 kJ is added to 10 moles of ethylene initially at 200 °C?

Answer 1

Answer: The final temperature when heat in the amount of 800 kJ is added to 10 moles of ethylene initially at $200^{o}C$ is $1529.63^{o}C$.

Explanation:

It is known that the heat capacity of ethylene is 2.145 J/g K. Hence, for 10 moles of ethylene its mass will be as follows.

      No. of moles = $\frac{\text{mass}}{\text{molar mass}}$

           10 mol = $\frac{\text{mass}}{28.05 g/mol}$                  

           mass = 280.5 g

Now, we know that relation between heat energy, mass and specific heat is as follows.

          q = $mC \times \Delta T$

 $800 \times 10^{3} J = 280.5 \times 2.145 J/g K \times (T - 473) K$

      $800 \times 10^{3} J = 601.67 \times (T - 473) K$

         1329.63 = T - 473

              T = 1802.63 K

or,              = $(1802.63 - 273)^{o}C$

                 = $1529.63^{o}C$

Thus, we can conclude that the final temperature when heat in the amount of 800 kJ is added to 10 moles of ethylene initially at $200^{o}C$ is $1529.63^{o}C$.