Skip to main content

Why is the equivalence point of the reaction between hydrochloric acid and sodium carbonate "somewhat acidic"?

The balanced chemical equation for the described reaction is as follows:


`HCl + Na_2CO_3 -> H_2CO_3 + NaCl ` .


The equivalence point is not at pH 7 but is slightly acidic.


The equivalence point is defined as the point during titration wherein the moles of added acid (or base) are equal to the moles of the base (or acid) being titrated. In titration of strong acids and bases, like the reaction of NaOH and...

The balanced chemical equation for the described reaction is as follows:


`HCl + Na_2CO_3 -> H_2CO_3 + NaCl ` .


The equivalence point is not at pH 7 but is slightly acidic.


The equivalence point is defined as the point during titration wherein the moles of added acid (or base) are equal to the moles of the base (or acid) being titrated. In titration of strong acids and bases, like the reaction of NaOH and HCl, the product is NaCl, a neutral salt, and water, a neutral substance. This is true for any strong acid and strong base -- the products will always be a neutral salt and water -- and hence, the pH of the resulting solution at the equivalence point is 7.


This is not the case, however, if one of the reacting species isn't a strong acid or a strong base. Sodium carbonate dissociates in water into its ions -- the sodium ion and the carbonate ion. The carbonate ion is a weak base. Since it is  a weak base, upon reaction with HCl, it produces its conjugate acid. The conjugate acid, just like any acid in a solution, will react with water to produce more hydronium ions. The generation of this extra hydronium makes the equivalence point of this given titration reaction slightly acidic.


In general, if a reaction is between a strong acid and a strong base, the equivalence point will be at pH 7. If it's between a strong acid and a weak base, it will be acidic. If it's between a weak base and a strong base, it will be basic.

Comments

Post a Comment

Popular posts from this blog

What is the meaning of "juggling fiends" in Macbeth?

Macbeth is beginning to realize that the three witches have been deceiving him since he first encountered them. Like jugglers, they have kept changing their forecasts in order create confusion. This is particularly apparent when the Second Apparition they raise in Act IV,   Scene 1 tells him that no man of woman born can overcome him in hand-to-hand battle--and then Macbeth finds himself confronted by the one man he has been avoiding out of a... Macbeth is beginning to realize that the three witches have been deceiving him since he first encountered them. Like jugglers, they have kept changing their forecasts in order create confusion. This is particularly apparent when the Second Apparition they raise in Act IV,   Scene 1 tells him that no man of woman born can overcome him in hand-to-hand battle--and then Macbeth finds himself confronted by the one man he has been avoiding out of a sense of guilt, and that man tells him: Despair thy charm. And let the angel whom thou still hast serve...
Post a Comment
Read more

In Martel's Life of Pi, how does writing a diary help Pi Patel build on his leadership skills?

At the end of chapter 73, Pi first divulges the fact that he had started a diary after about a week alone at sea. Pi claims that he wrote about "practical stuff" (208) such as what he caught for food, foreseeable problems and solutions, Richard Parker, and reflections about specific events that occurred. In a sense, Pi is the captain of his ship; therefore, he must take responsibility for himself and his crew. He can... At the end of chapter 73, Pi first divulges the fact that he had started a diary after about a week alone at sea. Pi claims that he wrote about "practical stuff" (208) such as what he caught for food, foreseeable problems and solutions, Richard Parker, and reflections about specific events that occurred. In a sense, Pi is the captain of his ship; therefore, he must take responsibility for himself and his crew. He can do this by writing down events, problems and solutions, and reflections to look back on when confronted with repeated problems. It can ...
Post a Comment
Read more

Why did Tybalt attack and kill Mercutio instead of Romeo, who he had originally been targeting?

Though Tybalt's quarrel is with Romeo, he begins the momentous duel in Act 3 by fighting with and killing Mercutio instead. Tybalt ultimately attacks Mercutio because the garrulous and hot-headed character insults Tybalt and goads him into a duel to protect Romeo's honor. From the beginning of the encounter in Act 3, Scene 1, it's clear that Mercutio is itching for a fight. For instance, when Tybalt signals that he wants to talk to Mercutio... Though Tybalt's quarrel is with Romeo, he begins the momentous duel in Act 3 by fighting with and killing Mercutio instead. Tybalt ultimately attacks Mercutio because the garrulous and hot-headed character insults Tybalt and goads him into a duel to protect Romeo's honor. From the beginning of the encounter in Act 3, Scene 1, it's clear that Mercutio is itching for a fight. For instance, when Tybalt signals that he wants to talk to Mercutio and Benvolio, Mercutio responds "And but one word with one of us?/ Couple it w...
Post a Comment
Read more