 So, we've already previously looked at neutralization reactions and started that whole process of identifying that neutralization reactions occur when we have a neutral product, that is water being produced and this occurs in a reaction between an acidic substance and a basic substance. Usually in the formation of water, a salt will also be produced. The salt is the ionic product of the anion donated by the acid and the cation from the base. In particular what we want to look at is the fact that the hydrogen ion or the proton from the acid is going to link in with the hydroxide ions from the base to form water. So if we were to summarize this and we had a look at this in a previous video, the net ionic equation is the hydrogen ion coming from the acid and the hydroxide ion coming from the base and these are forming together water molecules. So this is our net ionic equation for a neutralization reaction and it's the reaction that we find very commonly when different acids and bases are put together. Neutralization reactions are very common reactions and they occur everywhere pretty much. Some of the examples that you need to, I guess, be able to be aware of and perhaps you might explore a few of these a little bit more in class, are some everyday applications that we either experience ourselves or have available around our homes and also some more broader industrial applications of different types of neutralization reactions. So one of the most common ones that we can discuss is the neutralization of stomach acids. So in our stomachs we produce hydrochloric acid of quite a high concentration and this is very important for protein digestion. In fact one of the things that we look at is the fact that pH is actually a very important component of a lot of our different body systems. Different types of biochemical reactions have optimum levels of performance at different pH values and not all of them at a neutral pH of 7. So therefore we, somewhere like the stomach where protein digestion occurs, this needs to occur or the enzymes that are part of protein digestion occur when the stomach is a very strongly acidic environment. So therefore we secrete hydrochloric acid, quite concentrated hydrochloric acid in order to achieve this. Now the problem is that sometimes this acid can build or can be secreted at the wrong time or because of the sorts of foods that we're consuming these acid levels can get very high. If we're going to control that or regulate that or address that concern, we need some sort of a substance that's going to neutralize that and that's why we will often take something known as an antacid, think of it as an antiacid. So something that's going to counteract the effect of an acid, we now know that an antiacid is a base and when the base reacts with the acid it neutralizes it to form carbon dioxide or to form water. For some of these, of course, carbon dioxide is also going to be a product. And if one of the key components of our antacid is a carbonate or a hydrogen carbonate, such as sodium, then it is going to produce carbon dioxide as well as the water. If we were to pick one of these other ones, such as say magnesium hydroxide, which a lot of these sorts of substances, which is contained in a lot of these sorts of antacid substances, then we can write our equation out here, magnesium hydroxide and that is going to that could be in a solid form or usually you'll put it in water, so it'll be an aqueous form and that will form magnesium chloride, which will be in solution and also water molecules and there'll be two water molecules for this particular one, which is balance that out a little bit. As I said, not just the stomach has a sensitivity to a particular pH value, but so do many other systems in our body and mouth where we start the digestion process, blood, pH is also needs to be maintained within a narrow range. And of course, there are other examples of cooking in our kitchens where we may use acids in our cooking bases in our cooking in order to change the flavours and sometimes even to produce carbon dioxide, to produce bubbles, fluffy doughs and things like that.