Learn about Junior Chemistry, Balancing 3, in this comprehensive video by bannanaiscool.
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Rob Lederer: Here I've got some sodium hydrogen carbonate on the scapula and I put it into the solution and we'll stir it around a bit, and I'm about to place this sodium hydrogen carbonate aqueous into a 5% solution of acetic acid, which is CH3COOH. Sure, it's baking soda and vinegar. Well, what's the reaction? Now, it's time to do some reaction chemistry. These replacement reactions single and double replacement are when we take chemicals that are ionic in nature put them in solution and react them either with another element or compound to get a rearrangement of chemicals on the other side. Here it comes. Watch this. Here is a piece of nickel and we put it into a solution of silver nitrate, this is AgNo3 Ag+ No3 together and it's Aqueous because it's a solution. I took an ionic crystal and I dissolved it to make a solutions AQ means Aqueous dissolved in water. Now what happens? How do these two chemicals react in solution? What we do is we take this metal, which is Nickel, and then we take the Silver here and we make them -- places that's a replacement reaction, but you have to maintain the proper charges when you are recombining to form the products. Watch. When the Nickel reacts with the silver nitrate, they change places and nickel goes with the nitrate. Nickel however, on your periodic table has what charge? Nickel is the most popular charge nickel, it's the two positive ones. So, when you are not told which one to use, you always use the one that's more popular, which is the Ni2+ which you might not use Ni2+ you might use Ni3+ or Ni+. Yes we told. But when you are not told hey, it is right there Ni2+. But nitrate is one of those polyatomic ions it's a negative one charge. So when these two come together, look at what they form it's (N03)2 there is two nitrates for every one nickel. Now, you need to check a chart called the solubility chart to be able to determine whether or not this is Aqueous or whether it comes out as a solid precipitate. Here is what that chart looks like. Here is the solubility chart right there. Now, how do you work this? Well, here are some very common ions, cations over here and some anions down here. If you can match the anion or cation up here with one that falls into this range here, then that says solubility greater than or equal to -- very soluble that means Aqueous. So, you'll just put aq next to that compound. But if any of these compounds match up with anything in here that means slightly soluble and you've got yourself a solid, so you put an S. So, when you look on that chart, here is the idea. Nothing ever precipitates with nitrate as you could see. So therefore, nickel and nitrate form a solution and precipitate as a solid. So, this remains aq just like this one was aq, but what goes off by itself now? Well, the silver goes off by itself. Now, how do we write silver -- by itself? Just ag. Not Ag2 it's not a group seven or anything like that. All we do is write silver and a solid and we have no charges left for anything up here. You never write those charges once you got the compounds written down. Now, there is your equation and it only is requiring you to get it balanced. So, let's do that. One nickel here, one there. One silver there, one there. It's easy. So, I have done. One nitrate here, two nitrate. See, I kept the No3 together when two No3s because No3 is on the other side too, so balance the whole thing the whole polyatomic ion together. We will have to balance them the nitrogen separately from the oxygen. It's fine. So, take a look. One No3 there two there. You got to put two in front here. Now, you got two No3, but you got two ags. Now, the entire equation is balanced in one two, one two. Let's do it another one.

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