Reactions of Acids

[00:00:00]so in the next of these introduction to chemistry videos we're going to review your understanding of acids and bases and salts and probably extend it a little bit from GCSE so the first thing we need to do is consider what we understand by the word acid this is probably a little bit more than what you said at GCSE and I see that a level is the substance that donates pH plus ions and sometimes in a level chemist you hear people refer to those as protons so a substance that donates protons might be another way that we would describe an acid and you might think well protons are inside the nucleus how can he expose ions B protons but if you just take a minute to consider what a huge plus ion is so let's just consider hydrogen in the periodic table looks like this in the third experiment and what that tells us is that there is one proton and therefore one electron because the neutral active but no neutrons because one take where one is nothing no neutrons in an element of hydrogen so one Aksum sorry if I have not the element but one proton and one electron so in the nucleus is one proton there's no neutrons i around the nucleus in shells there's one electron so if we consider the h plus iron well it still has the one proton in the nucleus but it's lost its electron so it now has no electrons are no neutrons and now you can maybe understand why a chemist might call a hit plus iron just the proton because that's all it is it's just one proton and no electrons are no neutrons so we might refer to an ACCI does a proton donor or as a substance that donate science so I'm gonna remind ourselves quickly off the formulas of those common acids so we've got HC yeah we should all know an h2 so4 I remember that nitric was hno3 Noack you might have come across a juice se it's one of the organic acids ch3co X you know organic chemistry means two carbons and there's two carbons in there and it's a carboxylic acids got this new group ethanoic acid these are some of our common assets now we've got a base so what is a base the base is the thing that accepts the H+ ion suit might be referred to as a proton acceptor from the acid it's gonna accept the protons so if we look at this example here we've got the hydroxide ion is the base this was called ammonia and this is called ammonium so what's the base who accepts the proton nh3 ammonia is a base so what's the difference in between a base and an alkaline well the only difference is an alkali these are base like a subset of abates and it's one that releases hydroxide ions when it's in solution so some of those are kind of obvious from the name just sodium hydroxide when it goes into a beaker does it separate into sodium ions and hydroxide ions it's got hydroxide ions in it so it's an alkaline potassium hydroxide it's got potassium ions and hydroxide ions it's non-flying so then it's ammonia how can that be when ammonia is formula was nh3 how can that have hydroxide ions well it's all to do with this word aqueous what does that mean that means with water when ammonia is in water what happens is it forms ammonium hydroxide and so this ammonia is actually n h 4o h and we can see the hydroxide ions in an exam you would be allowed to just write an inch 3/8 Q awesome look at Chris ammonia it's not some formula ammonia and air Q means aqueous or you could write n h 4o h but most people would tend to just write this as the formula of ammonia pastels reporters right Savannah Stoltz this is a definition that you probably didn't use that GCSE or if you did you said it's just when acids and alkalis react you can't use that at a level it's probably one of the most useful definitions to get equations right it's formed when the hydrogen ions of an acid I replaced by metal are ammonium ion so we're going to tip hydrogen ions and swap them for a metal or an ammonium ion so if I want to make something for I'd like sodium chloride or potassium chloride and magnesium chloride I need to think which acid content to myself which I said hydrochloric acid yeah and if I swap the hitch in here CL for a metal I could swap it for magnesium I do need to remember that magnesium two plus serve to balance it I'll need two chloride ions mg ccl2 but I'm swapping the HS for metals so these salts are made from that hydrochloric acid sulfates are made from [Music] acid h2so4 we've got some examples of sulfate the one that you might have made at school copper ii sulfate it's made from sulfuric acid where we swapped the hydrogens in sulfuric acid for the metal copper now there's 2 hitches because each one of them is 1 plus but there's only one see because it's 2 plus nitrates are formed from nitric acid hno3 sodium nitrate do calcium group two with two nitrates phosphates are formed from acid where we replacing the high extremes of phosphoric acid the hydrogen ions is metals so if we replace it with aluminium which is three plus all three hydrogen is replaced by one aluminium three one pluses is the same as a three plus if we had to cope with something like calcium phosphate that would be a bit trickier because calcium is in group two so we would need three calcium's two phosphate ions the phosphate iron must be so what we do we need to do here we need to go backwards work backwards the formula of the acid so what I would do some of these you think are the too easy for this method but it's better to know the method and apply it than to not know it mg SFR what's it made from it's made from energy to us for two - that's magnesium sulfate so what acid contains sf4 how many pitches to balance two - two - H pluses to balance s so far too - calcium phosphate is made from calcium ions it is there must be three of these and to balance two phosphates so the acid would be a ch3 ammonium nitrate so we've replaced the hydrogen with a metal or ammonium so we get rid of the ammonium iron which is this bit yeah we're getting rid of that and we're replacing it with a hydrogen a hydrogen has got one positive charge so we just replace it it's hno3 now this is where if you were just knowing the formulas of some acids you would fall apart because ka no2 is made from K which is in Group 1 so 1 plus I've never heard of this no.2 thing before but given that it was 1 K with one no.2 then the charge on it must be 1 minus coz 1 k plus would need one no.2 - to balance it so then I need to think of what goes with the no.2 to make it an acid and it's a hitch and H has the 1 plus charge so how many catches would you need for an a no - one - just need one hitch no.2 these two things these two are both called nitric acid but one of them is called nitric 5 and one of them is called nitric 3 we will learn about that later in the class but they are both types of nitric acid so magnesium ions are mg 2 plus which means this SS 3 that I've not seen before are must be 2 - to balance the 2 plus and I Father acid must have 2 hydrogen's in it to balance out the two minuses this is made from ch3coo and I'm not sure about that but I know that na is na plus so this must be a - hi Dan I am back on to that that's going to be ethanoic acid so really the last little section of this video is remind ourselves of what happens when acid reacts so acids can react with alkalis our bases to make salt some water with metals to make salt and hydrogen and with carbonates or hydrogen carbonates to make salt and water and carbon dioxide I'm going to just do now and this will be really useful later in the course just I'm gonna highlight this one the other four these four would all found as neutralization because they [Music] neutralization this is actually a redox reaction but it's still a reaction about six which is why we're gonna cover in this section so first of all we're gonna look at these decide which one of the types and then you're going to use your rules for writing formulas and balancing equations and coming up with formulas of salts to have a go so we're because we wanted together first thing I'm gonna do is decide which type nitric acid is an acid music sodium hydroxide go back to my definitions I know that hydroxides are alkaline so this is acid plus Alki makes salt plus water what would be the salt of nitric acid it's going to be a nitrate where replaced the hydrogen with the metal so it's going to be sodium nitrate plus water I want you to do now pause the video put in all the formulas of those things using I really a welcome formula and balance equation again using the early work on balancing equations okay so we should have got that balances without any numbers sodium nitrate plus water so our second example we've got hydrochloric acid plus magnesium oxide now oxides our basis this is a super space makes salt plus water the salt of hydrochloric acid is chlorite or replace the hydrogen with the metal so it's going to be magnesium chloride again pause the video and have a go at balancing the equation so I've written the farmers in but haven't balanced it just to remind you about that map to a rule so 1 mg 1 mg I balanced the metals now I'm going to balance the thing that isn't carbon hydrogen oxygen so the CL 2 cialis and put to see hours in front of the ax head to in front the acid and then to here chose to here choose to us no one Oh even wanna so that's balancing the equation see if you can finish the page see if you can identify the time put the products and write the formulas and balance the equations very good leave that on for a minute so you can check through your answers and so we've got each of the different types there we started off with us it was our tire then we went to a surplus base a surplus metal passive plus carbonate and then acid plus hydrogen carbonate and we balanced every single one of them making the salt so replacing the hydrogen's of the acid with the metal iron and water and carbon dioxide in these ones and in the bottom ones we had watch them come there upside top ones we had hydrogen or water just check that you can write and balance equations for acid reactions it's very very common at a-level chemistry