[Music] Hi and welcome back to free scienceless.co.uk. By the end of this video, you should be able to describe the procedure for carrying out a titration. This is for students studying triple chemistry only. This is a required practical, so it's highly likely there'll be a specific question on this in your exam. So, let's start by looking at what's meant by a titration. Take a look at this reaction. We've got sulfuric acid reacting with the alkali sodium hydroxide. This is called a neutralization reaction. Imagine that we have a certain volume of the alkali sodium hydroxide and we know the concentration. If we know the volume of sulfuric acid that we need to neutralize the alkali, we can use this to work out the concentration of the acid. Now, this sounds tricky, but titrations are actually quite straightforward. In the next video, we look at the calculations. In this video, we're going to look at the stages involved in the titration, and I'd recommend that you learn these stages. First, we use a pipette to transfer 25 cm cubed of sodium hydroxide solution into a conicle flask. The conicle flask reduces the risk of splashing. There is one point I need to mention about using a pipette. Normally, we'd use a pipette filler to draw liquid into the pipette. It's very important that you allow the liquid to drain out of the pipette rather than blowing it out using the pipet filler. Blowing the liquid out will give you an incorrect volume. Next, we add five drops of an indicator such as methile orange to the alkali in the conicle flask. We could use other indicators such as phenylthaline. Next, we place the conicle flask on a white tile so we can see a color change more clearly. We now fill a borete with sulfuric acid. Now we add acid to the alkali until the solution is neutral. With methile orange, the color change will be from yellow to permanently red. We need to add just enough acid for this to happen. So once we start to see a color change, we now add the acid drop by drop until the solution is neutral. I should also point out that it's important to swirl the solution to make sure that the acid and alkaline mix. Finally, we read the volume of acid added from the borete. It's important that this is done correctly. So, I'm going to discuss that now. When reading the borete, you need to make sure that your eye is level with the surface of the liquid. The surface of the liquid naturally curves. Scientists call this the meniscus, and I'm showing you that here. We always read the bureete at the bottom of the meniscus. So in this case, the reading is 17.9 cm cubed. Normally when carrying out a titration such as this, we repeat the titration several times until we get two readings within 0.1 cm cubed. We then take a mean of these for our final volume. Okay, so now we know the volume and concentration of the alkali and the volume of acid needed to neutralize it. So we can use these to calculate the concentration of the acid. In the next video, we'll see how to carry out this calculation. Remember, you'll find plenty of questions on carrying out a titration in my revision workbook, and you can get that by clicking on the link above. Okay, so hopefully now you can describe the procedure for carrying out a titration. [Music]