 Let's explore how acids and bases react with stuff. We'll first start by looking at how acids react with metals. To understand acid reaction, just remember one thing. That acids are H plus donors and then everything will make sense. For example, what happens if you have magnesium reacting with hydrochloric acid? Well hydrochloric acid being the acid donates its H plus ions and now magnesium can combine with chlorine to form magnesium chloride and the hydrogen will be liberated. So you get magnesium chloride plus hydrogen gas. Now why do we get MgCl2? Well because remember Mg has a valency of 2 so it'll combine with 2 of the chlorine chlorine atoms. So this is not a balanced equation yet but can you balance it? Can you pause and see if you can balance it yourself first? All right, so since you have 2Cl and 2H just make 2 here and we are balanced and so you look you get a salt magnesium chloride and you have hydrogen gas liberated. Let's try one more. What happens if you have zinc reacting with hydrochloric acid? Again, pause the video and see what you will get. All right, again hydrochloric acid will donate its H plus ions and therefore zinc will now react with chlorine to get zinc chloride and you'll have H2 gas liberated and just like before you have to balance this equation this way. And so in general what can we say? What happens when metals react with acids? Well metals react with acids to give you a salt and you get hydrogen gas. Makes sense, right? In fact, let's actually look at an experiment now. So here we are going to add zinc metal into HCl which is already added into the into the conical flask. And now you will see zinc chloride is being formed but H2 gas is being released as bubbles. Now how do we know it's H2 gas? How do we know that it's H2 gas? Remember H2 gas is flammable which means if I were to keep it near a flame it'll actually kind of sort of explode. You'll get a pop sound and let's look at it. Let's look at it. So we're going to put H2 gas is coming out. We're going to put a flame right next to it. It's going to have a pop sound. Whoa! That was not a pop! That exploded! That is dangerous! There was too much hydrogen coming out. Do not try this at home. If you are doing this experiment in school make sure that you're wearing your footprints and you have an adult nearby. So hopefully you'll never forget that metals react with acids to give you metal salts and hydrogen gas. Let's move on to the next one. Let's consider now what happens when you have a base reacting with metals. For this remember that base are hydrogen ion acceptors. They love to accept hydrogen ions but guess what? Metals do not give you hydrogen ions and therefore bases will usually not react with metal. There will be absolutely no reaction with bases and metals but there are some exceptions. Let me give you an example. If you have zinc reacting with a base which is NaOH well technically nothing should happen because zinc cannot donate zinc cannot provide H plus ions to NaOH and NaOH cannot accept H plus ions because it doesn't divide it. For example if you have zinc reacting with NaOH well in general nothing should happen because zinc you know there's no H plus ion for NaOH to accept but zinc is such a powerful metal such a such a reactive metal that it's actually going to kick that hydrogen out and so you will actually get sodium zincate plus hydrogen gas. This is a very rare exceptional case. It's a complex salt we call it and but since this is exceptional we'll call it as not a general rule. In general we will say that this only works for very reactive elements and in general bases do not react with metal. Okay let's move on to the third case. What happens when acids react with metal carbonates or bicarbonates? Well let's see you have a sodium carbonate over here that's reacting with HCl. What's going to happen? Well just like before HCl is going to donate H plus ions. Now all we need to look at what's going to happen well that H plus ion can now combine with CO3 over here and we can get a few things we can get carbon dioxide and we can get water because there is O here it can combine with H and NA can combine with Cl to get sodium chloride and so let's see what we get. We get sodium chloride, we get carbon dioxide and we get water and again we have to balance this. You can see there's a H2 here but there's only one H so this is not balanced but we'll just go ahead and balance it. Two here and two here we are done. Okay let's look at one more. What happens now if you have a sodium a bicarbonate reacting with HCl? Why don't you pause the video and see if you can try the answer this yourself. Okay again hydrochloric acid will donate its H plus ions. This time the hydro again H plus ions can combine with these things. You can get a H2O, you can get a carbon dioxide and NA can combine with Cl which means I think we should get the same answer. We should get sodium chloride plus carbon dioxide plus water. We get exactly the same thing but the beautiful thing about this one is as you can see it's already balanced. This is perfectly already balanced which means what happens when you have metals reacting with the sorry what happens when you have metal carbonate or metal bicarbonate reacting with acids? Well they will react with acids to give you a salt just like before but this time you also get carbon dioxide and water. Why? Because the H plus ions can react with these things to give you that. But before we go proceed one question we can have is is there a test to check that the evolved gas is actually carbon dioxide? Like is there a test for that? And the answer is yes there is a test for that. How do you test it? Well if you take carbon calcium hydroxide which is what we call lime water. Lime water does not mean water that comes out from squeezing lemon. No not talking about lemon juice. Calcium hydroxide usually anything with calcium we call it as lime. So calcium hydroxide lime water if you pass carbon dioxide with calcium hydroxide if you if you combine them then you will get some kind of a white precipitate. That white precipitate will be calcium carbonate. So this carbon dioxide will combine over here with calcium to give you calcium carbonate and you get water. This is how you know that this gas was CO2 because it gives you white precipitate when it pass through lime water. But here's the thing if you add even more carbon dioxide to this to calcium carbonate to this particular solution then calcium carbonate will further combine with calcium sorry carbon dioxide will further combine with calcium carbonate to give you calcium bicarbonate and that becomes colorless. So this is a beautiful test in which you first pass CO2 to give you white color then you pass even more CO2 and it becomes colorless. Now let's see a part of this let's again do this reaction. So in this case we are going to add I think this is sodium bicarbonate and we're going to put some acid I think we're putting acidic acid and look look you're getting these effervescence right these bubbles that is your carbon dioxide that was coming out which we saw earlier right now how do we know that this carbon dioxide what we'll do that test. So here we have lime water this is our lime water which is calcium hydroxide we're going to pass that same gas through it and let's see what's going to happen all right we're going to pass that same gas you're passing that gas into it and look it turns milky that white precipitate you're getting calcium carbonate over there and this is how we know that the gas that was passed is carbon dioxide and of course if you pass even more carbon dioxide it will further react with calcium carbonate to give you calcium bicarbonate but that requires way more carbon dioxide and we'll not do that reaction and so this is where we'll stop that brings us to the fourth and the final one how does acids react with base well let's see if you have a hydrochloric acid reacting with NaOH what's going to happen this is like the perfect reaction for them because remember this acids give you H plus ions sodium hydroxide or base are H plus acceptors so you have H plus donors and you have H plus acceptors oh it's going to be so beautiful so it's going to donate is H plus and this is going to accept it and that OH is going to accept that H to give you H2O and Na will combine with Cl to give you NaCl so you'll get NaCl plus H2O and so in general we can say acids and base react to give you salt and water this is what we call a neutralization reaction so this is one of the ways in which you can get salt acids and bases always react to give salt and water all right so with all of this let's just summarize what we learned what happens when acids react with metals remember because acids are H plus donors metals will form a salt and you get hydrogen gas so you get salt plus hydrogen gas what happens if base reacts with metals general nothing because base are hydrogen acceptors metals do not give you hydrogen ions so there's nothing to accept and so in general there'll be no reaction there are some exceptional cases but don't worry about them what happens when acids react with metal bicarbonates and carbonates something very similar happens there will be a salt form but instead of hydrogen gas the hydrogen can now react with this carbonates and bicarbonates to give you carbon dioxide and water so look just like before you get a salt but now that hydrogen that was released instead of forming a hydrogen gas it will react with the carbonates and bicarbonates to give you carbon dioxide and water and finally what happens when acids react with base oh it's just like the perfect reaction you get a salt and water