Which of the following solutions is a buffer? (a) A solution made by mixing 100 mL of 0.100 M CH3COOH and 50 mL of 0.100 M NaOH, (b) a solution made by mixing 100 mL of 0.100 M CH3COOH and 500 mL of 0.100 M NaOH, (c) A solution made by mixing 100 mL of 0.100 M CH3COOH and 50 mL of 0.100 M HCl, (d) A solution made by mixing 100 mL of 0.100 M CH3COOK and 50 mL of 0.100 M KCl.

Video transcript

Hello everyone. Today, we have the following problem. Which of the following is a buffer. Let's go through each answer. Choice A says that we mix 100 mL of 0.1 50 molar of acetic acid and 500 mL of 0.1 50 sodium hydroxide. So we have a strong base here but notice that we have the same concentration of that strong base with a weak acid and buffers. While they contain an acid in a base, the base needs to be in greater concentration when it is paired with a weak acid. And so because our weak acid is because we are adding less volume of our weak acid, this can therefore not be neutralized and form a buffer. So in choice A is not correct. If you're looking at choice B, we have 0.1 50 molar of acetic acid and 50 mL of 0.1 50 molar sodium hydroxide. So we will actually generate a weak acid conjugate base pair. So for answer choice B, we will actually generate the following and we have that sodium for a spectator ion. And so because we form a weak acid conjugate base pair and we see that the weaker acid is in less, in greater amount. We can say that B is a buffer. Andoy C is not a buffer because the resulting solution is a strong acid. And the hydrochloric acid will determine the hydro concentration and the ph and then with deep, we have our potassium acetate and our potassium chloride. And these are two salts and two salts cannot possibly form a buffer. And therefore, and choice D is incorrect. So we can conclude that our answer is and choice B overall, I hope it helped hands on next time.