Videos

Balancing Chemical Equations Notes

Added Apr 29, 2021 •

Copy this URL:
Embed code:	<iframe class="edlio-embed-player" type="text/html" width="640" height="360" src="//jhs.jisd.org/apps/embed/?v=316838" frameborder="0" allowfullscreen></iframe> Change dimensions

Show Transcript

they're going to talk about balancing chemical equation the law of conservation of mass says that matter is not created or destroyed in ordinary chemical reaction and what we're talking about right now ordinary chemical reactions to begin with began with a warm-up question in class how many CL chlorine atoms are in mgcl2 magnesium chloride where you look at the subscripts to next to the Sea on means there's two chlorine atoms and I've often compared this to the symbols for element on the periodic table those are like the alphabet in English a formula like we have here in UCL to that's like a word and then what we're learning today or equations would you like sentences in the chemical language so you'll find it on the worksheet this is a set of chemical equation here at the top we have a reactant on the left plus another reactant two things react to yield that's with the arrow reads two products in this case to have CH4 + 202 yield CO2 N2 H2 up that's the combustion methane with oxygen to create carbon dioxide in water and we have to have it balanced that's why we put these coefficients in here this number just like in math 2 x 2 is the coefficient the two in front of o2 the coefficient for the first of all to balance an equation you need to use coefficients with your numbers placed in front of chemical symbols and formulas the first step to balancing it is counting the atoms now showing example here in just a moment we're going to look at how many atoms of carbon there are in the reactants how many atoms of hydrogen how many atoms of oxygen we're going to compare that on both sides to each other so to do this you multiply each element subscript by its coefficient sample hearing carbon tetrahydride or methane carbon has no subscript so it's the one that's the third point on this slide hydrogen has four is a subscription there's one carbon atom combine weekly with four hydrogen atoms then you do the same thing with oxygen it has two times the subscript of to sew two times two is four so there's one carbon 4 hydrogen and four oxygen atoms in the reactants of this it is another way to look at it in the picture format this is that same carbon with for hydrogen combined with for oxygen notice over here in the right you have for oxygen for and you end up with four red for White's you got four wives which represent the hydrogen one carbon on both side makes it a balanced reaction so you can draw the pictures on simple equation if drawing helps you out step for if it has no coefficient of course you use one so subscripts or coefficients if none of their use of one if they're there is the number given and the reactants and the products are on the right so every I'm over here has to end up over here by comparing it to Lagos by have Legos and I've built an airplane I could take them apart and I can build maybe a fire truck out of it but the steel the same blocks the same building blocks are there Adam start off in the reactants they can broken apart and rearrange but the same atoms have to end up in products so again atoms are not created or destroyed there's the same number on both sides so we put coefficients to make that happen here's an example that give you number 6 on a case of balance which you should have from the assignment there in teams to iron + 3 o2 molecules this is equal that should be a yield has some number coefficient in a moment of iron oxide fe203 so to do this the way I like to start as I'll draw a line at the arrow on this case I have an equal but it should be an arrow so I draw line and then I want to count the number of atoms on both sides so we have iron and oxygen on the left some multiplying by the and we have iron auction on the right multiply the coefficient of iron 2 times of subscript have to iron and 3 * 2 we have 6 oxygen now for the right we just have subscripts there's nothing really to multiply 2 and 3 to iron 2 hours okay 6 oxygen 3 oxygen that's unbalanced that doesn't work you can't do that that breaks the law conservation of mass we had some oxygen atoms just disappear we don't do that so we have to put a coefficient so I would look at the side that's down three here we need to get that 26 so what times 3 equals 6 another way to look at that made me feel like algebra 3x equals 6 solve for x with three times to equal to put a coefficient of 2 do that that changes that changes the two-door for cuz it's now two times to change the 3 to 6 cool we're balanced write 6 oxygen 6 oxygen 400 we only have two what would change the coefficient we're not stuck with what they gave us in the problem that's a four to equal out to the iron cuz there's no subscript so we scratch out there so now we have poor iron for iron for iron 6 oxygen 6 oxygen is no longer an unbalanced now we're balanced and that's how you balance a chemical equation just go back and forth no matter how many times it takes to you end up balance there's more difficult equations in this but the rest case of balance is just like this paper you can draw them out if that if you like that like the pictures in this PowerPoint work or you could just use the math likes on this screen if you have any questions feel free to message me thank you

Uploaded by James Dorman.

Videos

Balancing Chemical Equations Notes

More videos from James Dorman