Multiple chemical equations

[audrey 1A]

For acids and bases that have multiple available hydrogens to deprotonate like H3PO4, do we keep removing the hydrogen until there are no more available? And if yes, how much does this affect the pKa/pKb?

[Julia_Belysheva_3K]

In general, polyprotic acids experience deprotonation until there are no H+ ions remaining on the acid. However, for the purpose of calculating pH, multiple deprotonations are only taken into account for H2SO4. In other cases, the subsequent deprotonations have no measurable impact on the pH. In earlier deprotonations, Ka is larger and pKa is smaller but in subsequent deprotonations, Ka becomes smaller and pKa grows larger.

[Emily Do 1F]

A TA mentioned to me that we will be explicitly told when something is a polyprotic acid, or be indicated that there is more than one Ka value.
To expand on Julia's response, pKa grows larger as an acid loses protons because it is becoming weaker and weaker. This is because once a proton is lost, the ion has a negative charge, which makes it more difficult to dissociate more and more.