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## Chemistry library

### Course: Chemistry library>Unit 14

Lesson 1: Buffer solutions

# Properties of buffers

AP.Chem:
SAP‑10 (EU)
,
SAP‑10.B (LO)
,
SAP‑10.B.1 (EK)
Buffer solutions contain high concentrations of both a weak acid and its conjugate base (or a weak base and its conjugate acid). Because these components can neutralize added H⁺ or OH⁻, buffers are highly resistant to changes in pH. Created by Jay.

## Want to join the conversation?

• what if we use strong acid in place of a weak acid
• The conjugate base of a strong acid would be an exceedingly weak base and so it would be severely limited in neutralizing additional acid. Essentially the addition of more acid would lower the pH even more so. The purpose of a buffer is to resist these drastic changes in pH so a strong acid buffer wouldn't really be achieving that.

All you'd have really is just an acidic solution capable of neutralizing additional base only.

Hope that helps.
• So I am struggling with the Henderson-Hasselbalch equation, and it wants me to know how to find the logarithm. It gives an example which is:
-----------------------
H2CO3 ←→ H+ + HCO3-
Ka = [H+][HCO3-]/[H2CO3] = 4.47*10^-7
This can be written as ...
4.47 = 10^.65 because o.65 is the logarithm of 4.47
--------------------------------------------------
my question and what has stumped me the most on this is how do you find that the Ka mentioned equals 4.47*10^-7 is there some equation or PH chart to figure that out?

any help would be awesome thanks.
(1 vote)
• It's not entirely clear what you're asking. Can you rephrase your question?
(1 vote)
• What is the exponential formula used when applying nitrate solutes to the titrations.
(1 vote)
• Doesn't the weak acid doesn't lower the pH?
(1 vote)
• The weak acid may cause the pH of the buffer solution to be less than 7, but the buffer solution still resists changes in pH.
(1 vote)
• Why does the OH ion react with the weak acid but not the H+ ions that would be present in the water due to dissociation? For example, the dissociation of an Alka Seltzer tablet. Wouldn't adding the OH react with the H+?
(1 vote)
• I'll assume you mean the H+ (or H3O+, or hydronium) which results from water autoionization.

If we add a base like hydroxide (OH-) to a buffer solution like this, it will react with any acids in the solution. So, both the weak acid and the hydronium from water will react with hydroxide. However, the concentration of hydronium from water is so small compared to that from the acid buffer so it plays no significant role in the pH. We only focus on the react of acid/base with the buffer since it predominantly decides the properties of the solution.

Hope that helps.
(1 vote)