The free energy profile as the reaction goes from reactants to products is a straight diagonal line from 50 kj/mol to 80 kj/mol. Is the reaction exothermic or endothermic? Does the reaction involve only pure solids and liquids? Is the equilibrium constant greater than, equal to or less than one? Is the change in the number of moles of gas equal to zero? At equilibrium, will products be formed?

To determine whether the reaction is exothermic or endothermic, you need to examine the change in free energy (∆G) during the reaction. The free energy profile you provided shows an increase from 50 kJ/mol to 80 kJ/mol. Since the free energy is increasing, this implies that the reaction is not releasing heat energy but rather absorbing it. Therefore, the reaction is endothermic.

The fact that the free energy profile only shows a straight line from reactants to products indicates that there are no energy barriers or intermediates involved, resulting in a simple reaction mechanism. This profile does not provide any information about the nature of the reactants or products, whether they are pure solids, liquids, or anything else.

To determine the equilibrium constant (K) for a reaction, you need more information than just the free energy profile. The equilibrium constant is determined by the relative concentrations of reactants and products at equilibrium. It can be greater than one, equal to one, or less than one, depending on the specific reaction and its reaction quotient (Q). Without further information, it is not possible to determine the exact value of the equilibrium constant.

The change in the number of moles of gas during the reaction is not indicated by the free energy profile. The change in the number of moles of gas affects the equilibrium constant, so without this information, we cannot determine whether it is equal to zero or any other value.

Finally, the free energy profile does not provide direct information about whether products will be formed at equilibrium. The formation of products at equilibrium depends on the reaction's equilibrium constant as well as the initial concentrations of reactants and products. Therefore, we cannot determine from the given information whether products will be formed at equilibrium.