we've now reached the first equivalence point within articulation. So at this point we have equal moles of our weak acid and strong base. Because they're equal in terms of moles, they will completely destroy one another. So at the end we have zero of each. But remember we have the conservation of mass, we're gonna form some of the we're gonna form some conjugate base. So at the end we have some of it remaining. In terms of calculating ph at this point we would discover what the formal concentration is of our conjugate base. So we'd say formal concentration which is F equals the initial concentration of my acid, which is 0.0.100 moller times the volume of the acid, Which is 50 MLS divided by the volume of the solution. So 50 mls of the acid and 50 mls of the strong base. That would give me a concentration of .050 moller. What we would then do is we plug in all the values that we need to figure out the concentration of H plus ions. Remember this here is the conjugate base but it represents the first intermediate form of my polyp protic acid. And this equation we should be familiar with because we used it when talking about calculations dealing with polyp Roddick acids. So K one we said was 7.5 times 10 to the minus three and K two. We said was 6.2 times 10 to the negative eight. Those will be the values we plug in for K one and K two, respectively. K W is 1.0 times 10 to the negative 14. When you plug all those values in, we find a concentration of H plus equal to 2.1 times 10 to the negative five molar. Since we know what the concentration of H plus is, we could find out what ph is which is just simply the negative log of H plus. So that will give us 4.70 for the ph at the first equivalence point. Remember we're dealing with the polyp product species. So we still have equivalent point number two and number three to go through as well as all the tight rations points in between and after them. So at this point we've seen that adding strong base is showing us an increase in our ph over time. So we'll continue onward with our discussion of adding even more strong base and seeing what else can the ph do as we're adding more of it.
