Now, we know to basically calculate, to determine whether reaction is actually exergonic or endergonic, we have to calculate what the gibsfree energy is of that reaction because ultimately it's the gift's free energy value that tells us whether reaction is spontaneous or non spontaneous. Now, the mathematical equation that allows us to actually calculate the magnitude of Gibbs free energy is this equation here. So the gibsfree energy of that particular reaction under those conditions is equal to the Gibbs free energy under standard conditions when the concentration of products and reactants is equal to one molar plus this entire quantity. So 2.33 times r t log q, where r is simply the gas constant, t is the temperature in Kelvin and q is the reaction quotient. And that tells us the ratio of the concentration of products to the reactants. Now, what exactly is the meaning of delta g?