What if pka

Select personalised content. Create a personalised content profile. Measure ad performance. Select basic ads. Create a personalised ads profile. Select personalised ads. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Share Flipboard Email. Anne Marie Helmenstine, Ph. Chemistry Expert. Helmenstine holds a Ph.

She has taught science courses at the high school, college, and graduate levels. Facebook Facebook Twitter Twitter. A lot of times, you just wanna know, you know, what's in your solution, depending on what you wanna do to your solution, if you wanna add things to it, maybe you wanna add some acid, you wanna add some base.

You wanna know what's going on. The Henderson-Hasselbalch equation gives you a really quick and easy way of doing that. So what we're gonna do, is we're gonna rearrange this equation to solve for this ratio that we might be interested in. And I don't know about you, but I actually find, well, laughs I find logs not super-intuitive sometimes.

So I'm actually going to get rid of the log by raising both sides to the 10th power. So what does this tell us? It may not look like it tells us a whole lot more, but actually, it tells us a lot. It tells us about the relative relationship and size between A minus and HA concentration.

So if we look at this, we can derive a couple relationships. So let's go ahead and look at all the possible scenarios for these three things. So anything to the zeroth power is equal to one. Which tells us that this ratio is equal to one.

And if A minus concentration over HA concentration is equal to one, that means that they have the same concentration. I forgot a minus sign there. This is a really helpful thing to remember. And this comes up a lot not just when you're talking about buffers by themselves, but also when you're doing titrations.

It is important to realize that pK a is not at all the same thing as pH: the former is an inherent property of a compound or functional group, while the latter is the measure of the hydronium ion concentration in a particular aqueous solution:.

Additional reagents can be added to a reaction solution to change the pH of the reaction conditions beyond the effects of an individual compound. An application of the Henderson-Hasselbach Equation is the ability to determine the relative acidity of compounds by comparing their pKa values. Some selected pKa values for compounds in the study of organic chemistry are shown bellow.

Since organic reactions can be performed in non-aqueous environments, the pH can exceed 14 and organic compounds can have pKa values above It is a variation on that line from the Wizard of Oz, "We don't live in water anymore.

It is a very good idea to commit to memory the approximate pK a ranges of the compounds above. If you are asked to say something about the basicity of ammonia NH 3 compared to that of ethoxide ion CH 3 CH 2 O - , for example, the relevant pK a values to consider are 9.

From these numbers, you know that ethoxide is the stronger base. Do not make the mistake of using the pK a value of this is the pK a of ammonia acting as an acid , and tells you how basic the NH 2 - ion is very basic! Biochemistry and organic chemistry texts often list the value as