Which of the following represents a buffer system? Explain.
a. H₃PO₃
b. NaNO₃
c. HC₂H₃O₂ and NaC₂H₃O₂
d. HCl and NaOH

Question

Which of the following represents a buffer system? Explain.

a. H₃PO₃

b. NaNO₃

c. HC₂H₃O₂ and NaC₂H₃O₂

d. HCl and NaOH

Accepted Answer

Welcome back, everyone identify which of the following will create a buffer system and provide justification for your answer. Choice. A states, sodium perchlorate, choice B states, nitric acid and potassium hydroxide. Choice C states, sulfurous acid and choice D states, nitrous acid and sodium nitrate. So let's begin first by recalling that a buffer system will resist drastic changes to P H and can either consist of a weak acid and its conjugate base or a weak base and its conjugate acid. So we're going to need to analyze the types of compounds that we have looking at. Choice a sodium per chlorine. We're going to recognize that sodium perchlorate consists of sodium, a group one, a metal on the periodic table as well as our perchlorate poly atomic anion. And in this case, because we have the combination of a metal and a poly atomic ion. This compound is thus ionic recall that ionic compounds are essentially going to be considered salts. And that is due to the fact that this salt is going to dissociate into dissolved ions being our sodium plus one ion and the perchlorate one minus an ion based on solubility rules for chlorides Now again, this is a salt and this would not be considered a buffer system. So we would say therefore, we will not form a buffer with just sodium perchlorate because we would have ultimately a salt solution. So we can rule out choice A so far and move on to choice B. In choice B, we have nitric acid, which we should recall is one of our strong acids in our textbooks and uh potassium hydroxide, which is also from our textbooks, one of our strong bases. Now we're going to recognize that we have the combination of a strong acid and strong base, which will result in a neutralization. And so that's at the equivalence point in a titration between a strong acid and a strong base recall that the P H would be neutral or seven. So this is therefore not going to be a buffer system. We do not have the presence of a weak acid and its conjugate base or a weak base and its conjugate acid because we have both strong acid and base compounds. So moving on, we would rule out Choice B and move on to choice C. In choice C. We have sulfurous acid and we're going to recognize that sulfurous acid from our textbooks is one of our strong acids and thus is not going to be a buffer yet again because we're missing a weak acid and it's conjugate base. So we can rule out choice C and now move on to choice D in which we have nitrous acid in which we should recognize is a weak acid. It's not in our textbook listed as a strong acid recall that weak acids will undergo partial dissociation because they are weak electrolytes. So because nitrous acid is a weak electrolyte, it's therefore again, going to undergo partial dissociation and undergo an equilibrium in which our nitrous acid is going to dissolve in water and be an equilibrium with its dissolved ions. A proton H plus, as well as our poly atomic ion, nitrite N 021 minus. Now recognize that our weak acid donated a proton to water. Now, we didn't show that in this reaction. However, we observe that we have the results of our acid donating a proton, which results in our conjugate base, which is our nitrite poly atomic ion, which forms. So we have the presence of a weak acid and its conjugate base nit trite. We're also given in choice D a second compound in which we have sodium nitrite. And so recognize that this consists of our metal, sodium and our poly atomic ion nitrite unless we have an ionic compound. So recall that this would be essentially a salt, sodium nitrate N A N 02, which is going to form its dissolved ions, sodium plus one cat and then our nit trite one minus anion. Now recognize that our sodium plus one ion is going to be a spectator in solution. Whereas our nitrite is again a conjugate base of our weak acid, nitrous acid. So thus both of these species contain either a conjugate base and a weak acid. And so we do have a buffer system in whole. So we can confirm that choice. D is the most correct choice and would be our final answer to complete this example as the following, that would create a buffer system being nitrous acid and sodium nitrate. So I hope that this made sense and let us know if you have any questions.

Which of the following represents a buffer system? Explain.
a. H₃PO₃
b. NaNO₃
c. HC₂H₃O₂ and NaC₂H₃O₂
d. HCl and NaOH

Verified video answer for a similar problem:

Key Concepts

Buffer System

Weak Acid and Conjugate Base

Strong Acid and Strong Base

Which of the following represents a buffer system? Explain.a. H3PO3b. NaNO3c. HC2H3O2 and NaC2H3O2d. HCl and NaOH

Verified video answer for a similar problem:

Key Concepts

Buffer System

Weak Acid and Conjugate Base

Strong Acid and Strong Base

Which of the following represents a buffer system? Explain.
a. H₃PO₃
b. NaNO₃
c. HC₂H₃O₂ and NaC₂H₃O₂
d. HCl and NaOH