The following pictures represent solutions at various stages in the titration of a weak base B with aqueous HCl. (Cl- ions and solvent water molecules have been omitted for clarity.)

. (b) Is the pH at the equivalence point more or less than 7?

Video transcript

Hello everyone today. We have the following question. Various stages of the thai tradition of a weak base ammonia and a strong acid hydrochloric acid are depicted by the following set of four diagrams, bromine ions and water molecules have been excluded for simplicity. What is the ph of the solution at the equivalence point? So first we need to define the equivalence point and that is when the number of moles of our acid are equal to the number of moles of our base. That is the equivalence point. So in this reaction we have our ammonia harmonia reacting with our hydroponic acid to form our ammonia yum ion and our bromide ion. We know that sense hydroponic assets are strong acid, it completely dissociates into h protons and bromide ions. So this will essentially look like this if we remove the spectator ion, which in this case is bromide because it appears both in the reactant and products. We end up with this reaction here, we have our ammonia plus our hydrogen proton to give us our ammonium ion at the equivalence point, there are both are ammonium ions and our bromide ions that we omitted as a spectator ion. And since bromide is the conjugate base of a strong acid, conjugate bases of strong assets aren't necessarily basic. So we have to just focus on this ammonium ion here. This ammonium ion is a weak acid. This makes the ph at the equivalence point acidic And that is because its p will be less than seven. So the ph at these at the equivalence point. So the ph at the equivalence point Will be less than seven. And with that we have answered the question overall, I do hope this helped, and until next time.