Question

If we reverse the reaction to read Z + W -> X + Y, the +deltaH would be a -delta H. Does this indicate that heat is given off or absorbed in the reverse reaction

Answer 1

Answer:

In this reaction heat is released

Explanation:

Exothemic Reactions : Those reactions in which heat is released when the products are  formed .

For such reaction The enthalpy change is negative.

$\Delta H= -$ for exothermic reaction

Endothermic Reactions : Those reaction which proceed by absorbing heat . Here heat is absorbed. The enthalpy change for such reactions is positive.

$\Delta H= +$

When the direction of reaction reverses , the value of H also changes.

In the given reaction,

$X + Y\rightarrow Z +Q$

$\Delta H= +$  = heat is absorbed

So,

$Z+Q\rightarrow X+Y$

$\Delta H= -$ = heat is released

Exothermic reactions are more spontaneous as compared to endothermic ractions. This means that they  proceed own their own . Only little amount of energy is supplied to exothermic reaction to produce the prodct.