 So here's the little list of analyses. So there's a couple of important things, soft drinks obviously, carbonic acid is the most likely chemical that you can analyze and perhaps seek to neutralize in soft drinks. Wines have a number of different complex chemicals associated with them, a few different types of acids. Often they're regarded as tartaric acid equivalents. This is not a precise measure, but it is an effective measure that you can use in order to carry out this particular process. Juices often have citric acid and other acids associated with citrus fruits. I guess it depends on the type of juice that you're analyzing. And of course the one important thing with juices is that they often have quite a distinctive color. Of course red wine also has quite a strong color and certain types of soft drinks can as well. And this makes it very important for us to think about the indicator that we're going to use when we carry out these chemical analyses. Different types of medicines, asperins may have an acid component to them as well. And some of them of course are antacids and may therefore be able to be neutralized by an acid. So there's a couple of different types, quite a range of different substances that you can use in order to analyze them for their acidic or basic content. So therefore I think what's most important when you're carrying out these experiments, hopefully in the laboratory, is to work out the answers to each of these questions. Firstly, is the solution acidic or basic? Therefore are we going to need to neutralize it with a base or an acid? Now beyond that we need to know a little bit more about the acid or the base because we need to know whether it's weak or strong. We've already had the joke about weak acid and weak base take weeks to carry out and so we know that we don't want, if we've got a weak acid for example in the substance that we're testing, we don't want to test that with a weak base. We want to test that with a strong base. So this is where an analysis of what type of acid or base that we have present in our substance can give us a bit of a clue as to what sort of neutralizing agent that we need. And of course that's the most important second question that we're looking at. So it's not just whether or not it's basic or acidic, it's also whether it's strong or weak. And most of the time it's going to be a strong acid or a strong base that's going to be used in neutralization because most of these are consumable types of substances and therefore we're not going to be consuming too many strong acids or strong bases. So that gives you a little bit of an idea of what sort of substance you can use in order to neutralize the substance that you're testing. Another important consideration is the need for standardization. So are you going to be able to use a primary standard for your neutralization or are you going to have to standardize a solution first? So if for example we were looking at wine and we wanted to determine the acidic content of wine, we know that the wine is going to contain weak acids. So therefore we're going to want to titrate with a strong base. Now the most obvious strong base for us to use would be sodium hydroxide, but sodium hydroxide is not a primary standard so therefore we'd have to have another step in the process which standardize the concentration of the sodium hydroxide and then we can use that to work out what the concentration of acids are in the wine. This is a very important thought process that you need to go through when you're applying your understanding of volumetric analysis and titration in particular to the analysis of common substances. And finally and most importantly is the selection of the indicator. Now this is going to be affected by both the color of the unknown. Remember we talked about the fact that we have juices, we could have red wine, we could have different substances which have certain colors and therefore the choice of an indicator may be affected by whether or not the color change is easy to see against the background. It might be that you need to have a dilution. So we can use the sample that we have but maybe we might dilute it by a factor of 10 for example just to remove some depth of color from our test solution in order to make it easier for us to see the color change with the indicator that we've chosen. And of course the selection of indicator is also based on whether we're looking at a strong acid, strong base, strong acid weak base or weak acid strong base. So depending on which type of titration we're carrying out that's going to affect our choice of indicator. These are some of the questions that hopefully go through your mind when you're starting to carry out titrations. All of the time when you're standing up to do these titrations you should have each of these questions in your head anyway. But in terms of specific application to the chemical analysis of a common household substance these are critical questions that we need to ask ourselves and have an answer to in order for us to be able to carry out these chemical analyses and hopefully you'll have opportunities to do that in class and thanks for watching.