 So here's a couple of models that we've used in class You may also have been playing around with the molly mod kits and I didn't have a photo of them So I haven't put one of them in at this stage, but we may update those later We did play with the blocks though and the blocks were a great way of trying to identify how we can transfer protons from one species to another so acid solutions for example where we have an ion like a chloride ion and the hydronium ion Can give us a representation of the fact that we have a strong acid which All of the molecules have been ionized But also something that is relatively concentrated as well as There's virtually no free water molecules in this particular example in the example To the right over here. We have three little representative water molecules and One little set of blocks representing an NH3 now. There's no ionization happening at all here So obviously what we would want is if this is going to act as a base. It's going to attract a proton Which is going to be transferred from one of those water molecules again this time There's only a small amount of water. So it's Probably a mid-range solution you might regard with a very very small amount of base in it in The third example you can see we've got lots and lots of water molecules. So this is a real Dilute solution because of the amount of water But also it must represent a weak Substance an acid or a base because there's no ionization that's going on here So our models are designed to help us to identify the degree of ionization and also the species that are present Once ionization or dissociation if it's a base occurs We've also got simulations and simulations are another great way of looking at how pH for example changes during a titration How the pH of a solution changes when we add a acid or a base to it and one of those changes occur gradually or Through some of those really steep the vertical lines that we've seen in some of the titration examples from previous videos So what we do with our models is they help us to explain some of the very important Characteristics and the most important characteristics that we need to be aware of is the fact that when we have a weak acid or a weak base the conjugate that's formed is opposite and It's possible that that conjugate event and may interact with water and That's why it's important because once we know whether we're dealing with a strong or a weak acid or base Then we can think about the conjugate and how that conjugate is going to interact with water and that interaction with water can create more H plus ions and push the pH into the acid range or more hydroxide ions and push it into the base range