Question

If the reaction is exothermic in the forward direction, which one of the following happens when reaction vessel is placed in a boiling water bath?  Circle one of the choices.

The green color turns more intense.

The green color turns less intense.

No change in color intensity.

Explain briefly your choice below (give reason):

Q2. Examine your observations in part (F) of the experiment and determine whether the following reversible reaction is exothermic or endothermic in the forward direction.  Give an explanation for your answer.  

Co(H2O)62+(aq)         +  4Cl-(aq)

CoCl42-(aq)    +   6 H2O

 

Answer 1

1.In an exothermic reaction heat or energy is released during the reaction. So, no external source of energy is required to carry out the reaction and if you supply heat to the reaction externally, there will be no change in the reaction. Here, there will be no change in the color intensity.

2. In this reaction, there is a formation of a tetrahedral complex from octahedral one. As we know the splitting parameter of tetrahedral complex is 0.44 of octahedral complex. As the energy gap of t_2g and e_g orbital is smaller in tetrahedral complex as compared to octahedral one, the reaction will be exothermic.