How many moles of Oh- do you need to make .1M H3PO4 have a pH of 7

To determine how many moles of OH- you need to make a solution of 0.1 M H3PO4 have a pH of 7, we need to consider the stoichiometry of the acid-base reaction.

H3PO4 is a triprotic acid, meaning it can donate three protons (H+ ions) in sequential steps. The reaction involving H3PO4 can be represented as follows:

H3PO4 + OH- -> H2PO4- + H2O (Equation 1)

In this case, each mole of H3PO4 reacts with one mole of OH- to produce one mole of H2PO4- and one mole of H2O.

Since we want to neutralize the H3PO4 solution and achieve a pH of 7, we need to convert all three protons of H3PO4 into water using OH- ions.

To calculate the number of moles of OH- required, we multiply the molarity of H3PO4 (0.1 M) by the volume of H3PO4 solution. However, we also need to consider that H3PO4 is a triprotic acid. Therefore, we need to multiply this by three to account for all three protons.

The calculation can be summarized as follows:

Moles of OH- = (0.1 M H3PO4) × (volume of H3PO4 in liters) × (3 moles OH- per mole H3PO4)

Keep in mind that the pH of a solution is related to the concentration of H+ ions, not OH- ions. The OH- ions from the reaction above will neutralize the H3PO4, but the pH will depend on the resulting concentration of H+ ions.