How does a balanced chemical equation illustrate that mass is never lost or gained in a chemical reaction?

Melting and boiling are endothermic processes. this means that these processes absorb energy from their surroundings in order to occur. use this information and the data you collected in the phase change gizmo to describe what happens to the temperature of water when you boil it, then explain why this result occurs.

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.

Consider the directing effects of the substituents on salicylamide and predict the possible structures of the iodination products. which do you think will be the major product?