 In this video, we are going to look at what dilutions are in chemistry, how to calculate them using a very easy equation and even extending to multiple dilutions which are called serial dilutions. I am sure you all already know that when you have orange squash and you dilute it, that just means you add water. It is the same in chemistry. Dilution is the process of adding water or another solvent to a solution to decrease the concentration. Exactly the same as your orange squash. You have it strong, or you can add more water and make it weaker. So you just need to remember that to dilute a solution means to add more solvent to a set amount of solute, therefore increasing the total amount of solution and decreasing the concentration. So, why do we dilute things in chemistry? In laboratories, solutions usually come in small concentrated volumes so that they are easy to store. You then need to dilute them to a known lesser concentration to use them, such as for titrations. But dilutions are really important for many other things too, such as for doctors and in microbiology. The good news is that there is a very easy equation to help us calculate dilutions. M1 V1 equals M2 V2. Let's have a look at where it comes from, and then we'll see what it means. Because the moles of the solute stays the same before and after diluting, we can say that moles of solute before dilution equals moles of solute after dilution. And then you should already know that moles of solute equals concentration times volume. We can substitute this in. And we get the concentration multiplied by volume before is equal to the concentration multiplied by volume after. Which is what this equation is telling us? I'm just going to pause this video for 5 seconds, long enough for you to save that equation to memory. M1 V1 equals M2 V2. Could it be any simpler? Let's now have a look at how to use this easy PZ equation. So we have our M1 V1 equals M2 V2 equation. Here our before values are M1 equals 1, and we don't know V1. Our post dilution values are M2 equals 0.6 and V2 equals 150 moles. Substituting in these values, we get 1 times V1 equals 0.6 times 150, so V1 equals 90 milliliters. That wasn't too tricky, was it? I told you it was a nice and easy equation. Watch the second part of this video to see how to use this equation for serial dilutions. Serial dilutions are just multiple dilutions and are no harder than the example we have just seen. You just need to remember that M1 V1 equals M2 V2 equation.