 We're going to start by looking at the reaction between acids, metal oxides, and metal hydroxides. The general formula is acid plus metal oxide goes to salt and water. Now first example, look at the reaction between hydrochloric acid and sodium oxide. Now to make the salt, we're going to look at the positive part of the basic section. So that's our sodium ion here, so sodium, and the negative part of the acid, the chloride ion, that's going to make up the other part of the salt. So we're going to get sodium chloride and water. We need to look at balancing, so we've got two hydrogens here but only one hydrogens here, so we need to double that one. Two sodiums here, two chlorines, two sodium chlorides, and now a balance. In this example we'll look at the reaction between nitric acid and magnesium oxide. So to figure out the salt we've got magnesium here, this is the positive part of our metal oxide, so that's going to be the positive part of the salt. We've got the negative part of the acid, so that's the nitrate ion, so NO3. Now we've got a bit of a problem. Magnesium has a two plus charge, the nitrate ion has a charge of minus one. So we need to do our Chrissy Crossy technique, so we get MgNO32, now we need to add water. Now we need to balance, so we've got two nitrates here but only one nitrate over here, so two nitrates, two hydrogens, let's have a look. One magnesium, one magnesium, four, five, six, seven oxygens, six, seven oxygens, so we're okay. So now a balance. Now we're going to look at the reaction between acids and metal hydroxides. Acid plus metal hydroxide, just like we had before, goes to salt and water. So let's look at some examples. So let's have hydrochloric acid reacting with sodium hydroxide. So our salt is made of a positive part of the base, so in this case it's the sodium ion. Negative part of the acids, in this case it's the chloride ion so we get sodium chloride again and we get water. Now let's have a look at balancing, two hydrogens, two hydrogens, one oxygen, one oxygen, one sodium, one sodium, one chloride, one chloride. So that one's all balanced. In our second example we're going to look at the reaction between sulfuric acid and magnesium hydroxide. So figure out the salt that's being produced, we've got the positive part of the base, it's going to be the magnesium here. The negative part of the acid is the sulfate ion. Now we've got magnesium has a charge of 2 plus, sulfate has a charge of 2 minus so they balance out that, so okay. And water, let's check our balancing. Two hydrogens, four hydrogens, so that means we're going to need to double the amount of water molecules. So we'll look at our oxygens, two oxygens, two oxygens, one sulfate ion, one magnesium, one magnesium, so we're balanced.