Question

For a reaction, AH = 176 kJ/mol and A SO = 0.285 kJ/(K•mol). At what

Answer 1

Answer:

C. T>617 K

Explanation:

We are given that

$\Delta H=176KJ/mol$

$\Delta S=0.285KJ/K\cdot mol$

We have to find the temperature at which the reaction is spontaneous.

When

$\Delta H>0, \Delta S>0$

Therefore, the reaction is spontaneous at certain range of temperature.

Option A is not true.

$\Delta G=\Delta H-T\Delta S$

When $\Delta G$ is negative, then  the reaction is spontaneous.

$\Delta G=176-0.285T$

When T<50

Suppose T=49 K

$\Delta G=176-49\times 0.285>0$

Therefore, $\Delta G is positive$.Hence, the  reaction is not spontaneous.

Option B is wrong.

C.T>617K

Suppose T=618 K

$\Delta G=176-0.285\times 618=-0.13$

Therefore, $\Delta G is negative$.Hence, the  reaction is spontaneous.

So, option C is true.

D.T<617 K

Suppose T=616 K

$\Delta G=176-0.285\times 616=0.44>0$

Therefore, $\Delta G is positive$.Hence, the  reaction is not spontaneous.

So, option D is not true.