What is a Buffer Solution?

In this JC2 webinar let's discuss what a buffer solution is and the difference between an acidic and alkaline buffer. A buffer is defined as a solution that maintains pH when small amounts of H+ or OH- is added. This definition tells us the function of the buffer, but it does not tell us what makes up the buffer. Personally I prefer to understand a buffer in this way: Since a buffer can maintain pH when H+ is added, a base must be present to remove the added H+. Similarly, since it can maintain pH when OH- is added, an acid must be present to remove the added OH-. Hence a buffer is nothing more than a mixture of acid and base. The acid and base must be related to each other in order to coexist in the same system, ie a conjugate acid-base pair. Typically we will learn there are 2 types of buffers: - acidic buffer is a mixture of weak acid and salt of conjugate base, eg CH3COOH + CH3COONa - alkaline buffer is a mixture of weak base and salt of conjugate acid, eg NH3 + NH4Cl Are these 2 buffer solutions really different? Acidic Buffer An acidic buffer is made up of a mixture of conjugate acid-base pair: Acid is CH3COOH that will remove OH- Base is CH3COO- that will remove H+ Alkaline Buffer An alkaline buffer is also made up of a mixture of conjugate acid-base pair: Acid is NH4+ that will remove OH- Base is NH3 that will remove H+ Fundamentally there is no real difference between an acidic and alkaline buffer. The only difference is the buffering range: - Acidic buffer maintains pH in the acidic region, ie pH less than 7 - Alkaline buffer maintains pH in the alkaline region, ie pH greater than 7 Topic: Buffer Solution, Physical Chemistry, A Level Chemistry, Singapore Please SUBSCRIBE to my channel and SHARE this video with your friends if you find it helpful! View the full video with description at my website https://chemistryguru.com.sg/what-is-buffer-solution Students who are interested in our LIVE Zoom webinars, please visit https://chemistryguru.com.sg/live-webinar