The PH formula is given as PH=-log(H+).  The H+ is the number of free ions of hydrogen.  A seven PH is considered neutral. Discuss what having a low PH and a high PH means. What does a 12 PH mean? How about a 2?  Which is more caustic?  Is either a good thing at extremely high or low values? Explain fully as to what a PH means to you and what you use it for.