That means if we add this little hydrochloric acid, our PH drops by five increments. That's equivalent to a 100,000 fold increase in the hydronium concentration of our mixture. So now let's add the same amount of sodium hydroxide, a base to our system. What will be the new PH? Well, first we calculate the Poh. And the Poh is equal to negative log of 0.1,
gives it two.