 Acid plus carbonate reactions are another example of a neutralization reaction, and that's because one of the products is water. Again, as we did with the previous examples, we will look at a general equation and then a specific example of that general case, and then we'll split things up into ionic equations to see what's happening for these types of neutralization reactions. So when we look at the reaction between an acid and a carbonate, we have a salt and water, which are the same two products that we got from our acid plus base reaction. But in addition, this time we also produce carbon dioxide gas. So when this reaction occurs, you will see bubbling or effervescence, and that's an indication of the presence of a gas. Of course, we can then test for the presence of that, for the actual identity of that gas using the lime water test, which will tell us that the gas that's being produced is actually carbon dioxide. So let's look at a specific example. Again, we'll choose hydrochloric acid, and this time sodium carbonate. So when we do this example, HCl in solution with sodium carbonate in solution is going to produce water, H2O liquid. Plus carbon dioxide, which is actually going to be a gas. And then the salt as previously will work out. Again, we've got the cation, which is coming from the base. I'm going to shock it here. There we go. There's green. Beautiful. There's the cation that's coming from the base or the carbonate in this case, and the anion, which is coming from the acid. The chlorine in this case. So as with our previous one, NaCl is our salt. This equation isn't balanced. So we just need to make sure that it is, and we put a 2 there and a 2 there and we'll be good. And of course, as previously, if you can work out whether your salts are soluble or not, then it means you can make sure you're putting the right subscripts in when you're writing these equations. So you see this equation looks very, very similar to our previous one where we looked at an acid plus base specific example of hydrochloric and sodium hydroxide. But now the presence of the carbonate and iron has resulted in the release or the production of carbon dioxide gas. So what does this look like in an ionic form? Because again, we've got some ions that are acting as spectators here, so we may be able to remove them. So we'll start again this time. We'll look at the ones that we've produced. I'll just leave the ions without the subscripts for now just because it's a little quicker as we're going through this exercise. So there's the acid hydrochloric acid. We have sodium and the carbonate ion. Now water is a liquid, so we don't separate it out. And carbon dioxide is a gas, so we don't separate it out. But we do put down the sodium ions and the chloride ions. So as we've done previously, we then look at our spectator ions and you can see we have two chloride ions here and two chloride ions here. And we have two sodium ions here and two sodium ions here. Which means that our net ionic equation this time, slightly different to the last one, is 2H+, in solution with a CO3 2- in solution produces water and carbon dioxide. Very important equation, that one. I'm going to come back and have a look at later on. As with our previous neutralization reaction, you can see that this production of water, which is a really important characteristic of neutralization reactions, hasn't occurred on its own this time. It's also occurred with the accompanying production of carbon dioxide gas.