 Here's the second one. And as I said, there's going to be a bit of a longer video of this one But that's because we need to work through some examples and I thought I'll put them all on together And you can start and stop them as you as you choose So here's a neutralization problem and in this neutralization problem. We need to know what volume of A point one molar sulfuric acid solution reacts completely with 17.8 mils of a point one five moles per liter potassium hydroxide solution So let's first of all write an equation H2S04 aqueous For the sulfuric acid is going to react with potassium hydroxide KOH aqueous It's an acid-based reaction. So it's going to form a salt and water So I can write water down straight away and it's also going to form a salt the salt is going to be a salt between the potassium and the sulfate and I know that the Potassium is a one plus and the sulfate has a two minus and I can actually get that from the high number of hydrogens if I'm not sure So that's the formula. I also use my nag sag to remember that group one Metals form soluble salts. So the K2SO4 will be a soluble salt and therefore aqueous My next step is to make sure that my equation is balanced And at this point I've got two K's over here. So I need two K's over here I've also got the hydrogens here are going to be contributing to water molecules and since I have Now two OH groups. I'm going to need two water molecules as well So here's an important thing a mole ratio of one to two to one to two To one. Okay, these numbers are the coefficients in front of each and obviously if there isn't one then we just put a one Now I have three very important variables I need to consider number of moles Which I'm going to put under the mole ratio because that's important volume which I put next because number of moles divided by volume is Equal to concentration. So what do I already know for the sulfuric acid? I know that the concentration is 0.1 molar and For the potassium hydroxide. I know that its concentration is 0.15 molar and also that it has a volume of 17.8 mils and as I did before I'm going to convert that straight away into 0.178 liters Now my way of solving these is to go up across and down. So I'm going to go up first. So I'm going to go this way So what I need to do is put my name on my CV So the number of moles of the potassium hydroxide is equal to 0.01 78 multiplied by 0.15. I've done those back to front concentration is point one five and And the volume is point zero one seven eight, but The multiplication is the same. So let's just do that point one five multiplied by Point zero one seven eight and what I have is two point six seven Times ten to the minus three Moles Now the next thing I do is I go across so my value is going to go in here 2.67 times 10 to the minus three now. I'm going to go across So the mole ratio was two to one which means that I need to halve that value in order to Know the number of moles of sulfuric acid that have reacted and so then I have a value now of 1.3 3.5 times 10 to the minus three and that's a number of moles of sulfuric acid which has reacted and now this time I need the volume so I know that n equals CV so therefore V Let's do another color V is going to be equal to N on C I know the number of moles now is one point three three five times ten to the minus three And I'm going to divide that by zero point one and when I do that. I get a value of 1.33 Times ten to the minus two if I multiply that by a thousand I'll get it into mills and I'll see that what I need is thirteen point three mills of my Sulfuric acid in order to fully neutralize the potassium hydroxide