But what if you don't know the standard free energies of formation for the products and reactants?

但是，如果您不知道产物和反应物的标准生成自由能怎么办？

The standard free energy of formation, written like this, is the change of free energy that occurs when a substance is formed from its elements at a standard state.

标准形成自由能， 这样写，是物质在标准状态下由其元素形成时发生的自由能变化。