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The Equivalence Point

Jules Bruno
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we've already answered this first part, we're gonna say at the equivalence point, the ph of a strong acid and strong base is equal 27. Now, if we're looking at a strong acid and a weak base, just remember whoever is weak will dictate what kind of solution you have at the end. Since we're dealing with a strong acid, the acid is stronger now than the base. So it's gonna say, since I'm stronger, I'm gonna want my solution at the end to be acidic. So anytime you're tight trading a weak acid, a strong base together at the equivalence point, the ph is going to be less than seven, it's gonna be acidic and it's acidic because the acid is stronger. Whoever is stronger, will tell us what kind of solution we have in the first example, They both were strong. So we wind up with a draw which means neutral. That's why the ph is equal to seven. Now, for the last scenario we have a weak acid and a strong base. Now the base is stronger. So it's going to dictate what kind of solution we have. Because we're dealing with a strong base, it's gonna want to have a basic solution. So the solution has to have a ph greater than seven at the equivalence point. So, just remember these fundamentals and as we start to do more acid and based filtration questions, keep this in mind as we face every type of question we're going to see. So just remember the equivalence point is when we have equal moles of acid and base. And depending on what we're tight trading, whether they both are strong or one is strong or weak, the equivalence point could have a ph equal to seven, less than seven or greater than seven.