 So as with our two previous videos, this is all about qualitative analysis, it's all about identifying within organic molecules particular functional groups and in this case what we're going to be looking for is the C00H functional group, double bonded oxygen and a single bond to a hydroxyl group. So how do we do it? Well the reactions that we've looked at previously are a little more complex and this is really about identifying an organic acid and because we simply need to identify it qualitatively we just need to say yes there is an acid functional group there. The simplest way for us to do that is to make sure that we have some simple things we can use. So obviously we need to make sure if we have the pH that we have a solution. So there's no point just sticking a pH meter into an organic acid in its liquid form because there'll be no ions present for you to measure. So what we have to do is we have to add the acid, we're going to add the acid to water which will then this will ionize and therefore it will increase the concentration of hydrogen ions in the solution and as a result when we test it with a pH we will have a pH which will now have dropped below seven and so therefore we should be able to determine that that particular compound that we've been looking at is an organic acid. Now it's not a particularly exciting test and obviously you can do that with universal indicator or or technology like pH meters or probes or data loggers. An alternative is to look at an acid reaction. So one nice little reaction for example is if we add a carbonate or even a bicarbonate ion what we're going to find is we will produce we will have effervescence. Okay which is just bubbles and the bubbles will be CO2. Of course we now know how to identify bubbles of carbon dioxide but those bubbles will indicate a reaction between an acid and a carbonate which we know is going to form a salt plus water plus our CO2 gas and that's the thing that's the easiest thing to see. Of course we could also react it with particular metals we could react it with bases and carry out neutralization reactions but the effervescent bubbling that we get when we add a carbonate is probably one of the simplest qualitative tests that we can identify.