Diazonium salts are explosively reactive intermediates for synthetic chemical reactions that must be handled with great care. These salts can decompose generating lots of heat and explosive generation of nitrogen gas. What can you predict about the thermodynamics of these reactions

Exothermic Reactions are taking place in this question

Explanation:

The chemical reaction mentioned in this question is Exothermic reaction as it releases heat and is explosive in nature.  

In fact exothermic reactions can release both heat and light. In such reactions the total energy of the products is less than the total energy of the reactants.  

Youre finding the number of molecules that make up that mass.

So first, you want to find the molecular mass (look at periodic table) of MgCl2 first, then divide mass (24.2g) by it to find moles.

moles=mass/Molecular mass then multiply the moles by avogadros number.