Which pka to choose

We will use a hypothetical acid A- H to achieve this:. One of the products on the right side is the protonated form conjugate acid of the alkoxide which is an alcohol.

The product in this reaction is a 3 o tertiary alcohol which are less acidic and are at the higher end of the alcohol p K a range An appropriate reagent for the protonation would be one with a p K a lower than For example, water can be used to protonate this intermediate:. Other options, in theory, can be phenol, acetic acid and all the inorganic acids such as HCl, H 2 SO 4 and etc.

However, in practice, not every acid-base reaction is suitable to carry out in a laboratory because these are one of the fastest and exothermic reactions and reaction very strong acids with very strong bases is often dangerous and the other factor is, of course, the pricing of the chemicals. To summarize, everything related to acid-base reactions can be, and is, explained by the p K a values and p K b for bases of the acids.

Choosing a proper base or an acid is no exception and when doing it, you need to keep in mind that the acid-base equilibrium is shifted to the weak acid higher pKa and base formation. To find a suitable acid , remember, for example, that any compound with a lower p K a value stronger acid can protonate another compound whose conjugate acid has a higher pKa value. Any base with a conjugate acid having a higher p K a value weaker acid can deprotonate another compound.

Determine, based on the p K a values, if each of the following compounds can be protonated by water. Write the corresponding chemical equation and remember that the equilibrium is shifted towards a weaker base and acid higher p K a value. Click here to Register! The pH of the solution should fall on the buffering range of a particular buffer solution. Explanation: Buffering range can be simply defined as the pH range wherein the solution can resists drastic changes in pH upon addition of small amounts of an acid or a base.

Related questions What is pH in acids and bases? What are pKa and pKb in acids and bases? What are Ka and Kb in acids and bases? How do you calculate the pH of a buffer solution? If you're seeing this message, it means we're having trouble loading external resources on our website.

To log in and use all the features of Khan Academy, please enable JavaScript in your browser. Donate Login Sign up Search for courses, skills, and videos. Science Chemistry library Buffers, titrations, and solubility equilibria Buffer solutions.

Introduction to buffers. Henderson—Hasselbalch equation. Common ion effect and buffers. Buffer solution pH calculations. Methods for preparing buffers.

Next lesson. Current timeTotal duration Google Classroom Facebook Twitter. And specifically, we're going to be talking mostly about this in terms of the Henderson-Hasselbalch equation. MOPS Buffer. TES Buffer. MOBS Buffer. TRIS Buffer. Glycylglycine Buffer. TAPS Buffer. CHES Buffer. CAPS Buffer.