Citric acid, C6H8O7, is a triprotic acid. It occurs naturally in citrus fruits like lemons and has applications in food flavouring and preservatives. A solution containing an unknown concentration of the acid is titrated with KOH. It requires 23.20 mL of 0.500 M KOH solution to titrate all three acidic protons in 100.00 mL of the citric acid solution. Calculate the molarity of the citric acid solution.

Video transcript

Hey everyone, we're told that the concentration of a 150 millimeter try protic acid solution was determined by dehydrating it with a potassium hydroxide solution were asked to determine the polarity of the tri protic acid solution. If 27.10 mL of 0.415 moller potassium hydroxide solution was required to neutralize all three acidic hydrogen. First. To answer this question, let's go ahead and determine our balanced chemical reaction. So we have our try protic acid and we're going to add potassium hydroxide since we were told that we titrate id it with potassium hydroxide. So we're going to end up with the conjugate base of our tri protic acid plus our water. To balance this out, we would need to add a coefficient of three prior to our potassium hydroxide and a coefficient of three prior to our water. Now we have our balanced chemical reaction. So we're asked to determine the polarity and we know that polarity is equivalent to moles over leaders. So let's first go ahead and calculate the moles of our try protic acid. Starting off with our 27.10 ml, we want to convert this into leaders So we know that we have 10- ml per one leader. Next continuing on with our dimensional analysis, We're going to multiply this by 0. mole of potassium hydroxide divided by leaders of potassium hydroxide. Next looking at our multiple ratios, we know that we have three mole a potassium hydroxide. Since we have that coalition of three in our balanced chemical reaction And this is per one mole of our tri protic acid. Now, when we calculate this out and cancel out all of our units, We end up with 3.748, 8 times 10 to the negative third mole of our try protic acid. Now to calculate our polarity, we're going to take that value of 3.7488 times 10 to the negative third mole of our try protic acid And divided by our ml. But first let's go ahead and convert this into leaders by using dimensional analysis and we know that we have 10 to the 3rd ml per one leader. So when we calculate this out, we end up with a more clarity of 0.0- moller of our tri protic acid. And this is going to be our final answer. Now, I hope that made sense. And let us know if you have any questions