Now, these questions and many others can be answered using a principle known as Lusciously as principle. And what this principle states is that whenever a system at equilibrium is stressed it will respond by shifting equilibrium in the direction that tends to decrease that stress. Now, let's look at three stresses temperature, pressure and concentrations. So let's begin with temperature. Suppose we have the following reaction in which 1 mol of among the gas state reacts with three moles of diatomic H two plus the gas state to produce two moles of ammonia alter the gas state and heat. So this is an exothermic reaction.