Analytic Chemistry | Analysis & Stages | Titrimetry

[00:00:00]Like I said, this particular stuff is very important in the sense that during a during revision time, you can just look at it because I want to take it step by step.

[00:00:10]I'll show us how questions can be asked or how it has been asked in the past.

[00:00:14]Now, we have analytical chemistry. We said it's a branch of chemistry that involves the separation, identification, and quantification of matter.

[00:00:24]Now, you want to analyze something, of course, um the branch of chemistry is analytical. For example, when I did my master's program, what my project was basically to analyze chicken feeds and meats to determine if the poultry owners normally add um growth hormones like steroids because I've seen a case where somebody will buy, you know, day-old chicken in less than 2 months, the chicken will all be, you know, big for sale. So, I carried I conducted such analysis, and trust me, I found lots and lots of growth hormones, which means most of the chickens we are eating, some are safe, some are not safe, all right? So, the process was analytical chemistry. So, of course, I separated um what I'm looking for from the matrix. There were processes I used, and then I I identify.

[00:01:13]Identification simply means to check whether it is present. Then quantification is to tell the amount, all right? Now, we said it involves the use of scientific instrument.

[00:01:24]Now, analysis basically, you know, analyzing something to find out the content or the type of stuff that is present.

[00:01:33]Now, we have Analysis is a process of examining part or all of the constituent present in a complex matter or substance.

[00:01:41]Please pay attention.

[00:01:44]The substance to be determined or analyzed is called analyte.

[00:01:48]Last year or some years back, they used to ask, "What are analytes?" They could just say, "What is an analyte?" They put a dash.

[00:01:56]So, you must know how to define an analyte. Analyte is substance to be determined or measured or probably substance of interest. Now, the process of measuring analyte is called what?

[00:02:08]Determination, all right? Now, we have two types of analysis. I'm very certain that many of us, even before we got to the university, you must have heard of qualitative and what?

[00:02:18]Now, let me ask, what is quantitative? Which one tells of the type?

[00:02:23]And which one tells of the amount?

[00:02:27]Quantitative talks about the what?

[00:02:32]Quantitative talks about the what?

[00:02:34]Amount. And qualitative talks about the what?

[00:02:37]Now, when when somebody say, "I want to conduct qualitative and quantitative analysis," as the name implies, quantity, amount. Now, qualitative analysis is just telling us what is present.

[00:02:50]Right? What is Qualitative analysis telling us what?

[00:02:54]What is present. While quantitative is telling us by how much.

[00:02:59]By what?

[00:03:00]How much. So, take note of that. There is no need for me to start giving us long notes. So, quantitative as the name implies, quantity, tells us how much of a substance is present, but qualitative tells of the type of substance that is present. For example, if I'm looking for um let's say, like what I did, for example, I did hormones um steroid analysis in chicken feeds. So, I did both of them.

[00:03:24]Now, we have stages in analytical processes. Now, I don't know how you're going to do it, but you need to actually take note of all these steps, step one to one by one. They can ask you, "What is stage three in analytical process?"

[00:03:41]Now, stages, the first one is to define the aim of the analytical process. Of course, please, I don't know how you're going to do this, but for me, I always have a way. How do I do it? I read it once, and I don't try to force it.

[00:03:53]Like I don't repeat it. For example, I don't say, "Define the the aim of the analyte."

[00:04:00]Define the aim of the analyte.

[00:04:02]You don't do that.

[00:04:04]You have headache, and you forget it.

[00:04:06]So, first thing's first, read out all of them. The first stage, please, this is not steps under gravimetry.

[00:04:14]This is stage in analytical what?

[00:04:16]Process. Define the aim of the analytical process. What do I want to achieve by this? I want to measure the amount of so-and-so. Select and develop a method. Now, the method to determine, if you go to the hospital, if you're going to you're If you're doing tests, the If you're doing malaria test, the method they are going to use is not going to be the same method if you're doing, let's say, some other tests, right? Different treatment, different what?

[00:04:42]Method.

[00:04:43]Okay.

[00:04:44]So, select and develop a method of analysis.

[00:04:48]Now, number three is sampling. Now, let me give you an example. What's What's What's is sampling?

[00:04:53]Sampling is actually taking a little out of a ball for the purpose of measurement to analysis. For the purpose of analysis.

[00:05:02]Your blood has, I think, how many liters Your body has how many liters of blood?

[00:05:06]How many?

[00:05:08]5 liters, right? But if you want to do analysis, they take just little amount of blood. So, they are taking sample.

[00:05:15]So, it's more like you're taking small quantity out of a large quantity for the purpose of what?

[00:05:22]Analysis. So, take note of that.

[00:05:23]Sampling the materials to be analyzed.

[00:05:26]Prepare the sample for analysis.

[00:05:28]Preparation is very important. What they don't take out of your blood, for those of us that are very used to um labs, I don't know, they they used to put it in either petri dish or glass glass plates, and then turn it as if they are cooking they are putting margarine inside soup.

[00:05:42]All right. So, your that is preparation.

[00:05:44]Now, measure the desired constituent.

[00:05:47]Measurement in this case can be either viewed in it under microscope, depending on what you're doing. Then the last one is what?

[00:05:55]Calculation and interpretation of results, and then evaluation of the result. You evaluate it. Oh, is this one high risk? Is it low risk? So, maybe if I block this stuff now and ask you, "What is the fifth stage?"

[00:06:13]I'm very certain that 85% of us cannot list this stuff one by one. You show me that.

[00:06:23]It Should we Should we try it?

[00:06:27]Or you guys know about?

[00:06:30]But but me now, I can actually try and remember all of them.

[00:06:37]I'm not going to look at it again, but I'll try and remember all of them. I can try, actually.

[00:06:42]So, today we want to talk about um titrimetric method of analysis, which is also called volumetric method of analysis. Now, many of us, we are very familiar with titration, right?

[00:06:54]Now, any method of analysis that involves titration is actually titrimetry.

[00:07:01]Any measure Any method of analysis that involves measurement of the weight of the substance, that's gravimetry.

[00:07:09]So, titrimetric method of analysis involves titration, which involves volume of liquid.

[00:07:16]So, we have different types of titration, but the type of titration we're going to be spending time to discuss today is actually acid-base titration. In acid-base titration, it looks like this.

[00:07:30]Now, this is a burette.

[00:07:36]And this is a glass.

[00:07:38]Now, this burette is actually on top of a retort stand.

[00:07:47]Right?

[00:07:48]Now, what's is always inside this guy is standard solution.

[00:07:58]Standard solution is always what's is actually inside this.

[00:08:02]And what's is always inside this guy is actually Standard solution is solution of known concentration, right?

[00:08:09]And what is inside this is the one that we are looking for.

[00:08:13]So, in the case of this analysis, we call this guy titrant or the analyte.

[00:08:21]What is inside this glass is always called the analyte or the titrant.

[00:08:25]Whereas, what is inside this guy is always called the titrant.

[00:08:33]What we have inside the glass is titrant.

[00:08:36]All right? Now, what are the principles of titration?

[00:08:42]All right, this book of lists complete this guy.

[00:08:45]Now, remember I told us we have different types of titration. We have acid-base.

[00:08:49]In acid-base titration, it's basically a case where the burette has either acid or a base, whereas the flask will now have the other one. Now, what's is inside the burette is actually what you know.

[00:09:04]That is standard solution.

[00:09:06]If what I'm looking for is the concentration of the base, I'll put base in a flask.

[00:09:12]If what I'm looking for is the concentration of the acid, I'll put acid in a flask. So, there is no rule that says acid must always be in the burette.

[00:09:22]All right? If you want to don't, you always put acid in the burette. Is it not so? Because you know the concentration of the acid.

[00:09:28]Okay.

[00:09:29]Now, the calculations involved in acid-base titration, we already know this formula.

[00:09:33]It's C A V A all over C B V B equals to Now, now this is concentration of the acid. This A stands for acid. This C stands for concentration.

[00:09:43]Now, this V is the volume of acid Now, majority of times, um you guys normally carry out more than one type more than one type up. Is it not so?

[00:09:53]You can do first type up, second type up, and third type up. So, the V is the average of the volume volume of the acid.

[00:10:00]So, this is always the average.

[00:10:02]Now, this is concentration of the base.

[00:10:04]Now, this volume of the base is the amount of base you put inside the flask.

[00:10:09]NA, number of moles of acid, NB is number of moles of base.

[00:10:14]Now, this can only be gotten from the balanced chemical equation.

[00:10:17]Now, if you any time this guy is equal to this, that is equivalence point. If the number of moles of acid is equal to the number of moles of base, you have what?

[00:10:28]Equivalence point. Now, let's look at this question here. They say a 15 mil of an HCl solution that's your VA.

[00:10:43]15 mil.

[00:10:46]HCl is an acid.

[00:10:49]Required 29.71 mil of this. This is a base.

[00:10:54]So, that's your VB.

[00:10:57]29.71 mil.

[00:11:01]Now, the base, the concentration of base, CB.

[00:11:06]Now, this is actually the base.

[00:11:10]And this is the acid.

[00:11:11]This is A and this is B.

[00:11:14]So, our CB is 0.01963 molar.

[00:11:21]To reach an end point with an indicator, calculate the molarity of the acid.

[00:11:25]Remember, molarity is the same thing as concentration of the acid.

[00:11:30]Now, this is what we are asked to find.

[00:11:32]Now, if you look at this, that is CA.

[00:11:36]So, they gave us this, they gave us this, they gave us this. This and this, they may not have given it to us, but you can get it from a balanced chemical equation.

[00:11:45]So, this becomes Mg OH + HCl.

[00:11:55]Now, this becomes When you balance this equation, you now have MgCl2 + water.

[00:12:06]Now, that's the balanced equation. Let me show you how we got to get that.

[00:12:10]Magnesium is 2 + OH is minus.

[00:12:14]This is H + and Cl minus.

[00:12:16]They exchange their charge.

[00:12:18]The negative of this guy comes to the positive of this.

[00:12:22]But if you look at this, the positive of this is 2.

[00:12:25]While the negative of this is 1. So, we need to add two of these to be able to cancel out this. That's how we got MgCl2. Now, when OH combines with HCl, we have All right. So, that's how we got that.

[00:12:37]So, we now say, if you look at this, let's see if the equation is balanced.

[00:12:42]But this is recording.

[00:12:45]Now, if the equation is balanced, let's check.

[00:12:49]Cl is 2 on the product side, Cl is 1.

[00:12:51]So, I need to put 2 here.

[00:12:54]If I put 2 here, water, I need Any hydrogen now becomes 2 here, 2 here. So, I need to put 2 here.

[00:13:02]So, we now have This is number This is Mg and this is Mg. So, this is 1 1 mole here.

[00:13:10]2 mole here. So, our NB is 1 mole, our NA is 2 moles.

[00:13:16]So, I'll now come here and I'll say Since what I'm looking for is CA, I'll now come here and say CA VA all over CB VB equals to NA all over NB. Now, I'll make CA the subject directly.

[00:13:41]But before I do that, I'll first cross multiply.

[00:13:44]It becomes CA VA NB CB VB NA.

[00:13:51]Now, make CA the subject of the formula.

[00:13:53]Divide both sides by VA NB. This becomes CA equals to CB VB NA.

[00:14:04]Now, insert your values. What is the value of CB?

[00:14:08]0.

[00:14:10]01963.

[00:14:13]What is the value of VB?

[00:14:16]29.71.

[00:14:18]What is the value of NA? 2.

[00:14:22]All over VA is 15.

[00:14:25]NB is 1.

[00:14:27]Please, someone should press your calculator.

[00:14:30]0.

[00:14:32]02 So, this Now, this ending part is very important because they could just make a statement and they put dash. So, please take note of these definitions very well.