Which of the following equations are balanced? Balance any that need it. (a) The thermite reacti

Which of the following equations are balanced? Balance any...

Key Concepts

Conservation of Mass

This fundamental principle in chemistry states that matter is neither created nor destroyed during a chemical reaction. When balancing chemical equations, every atom present in the reactants must appear in the products, ensuring that the total mass remains constant throughout the reaction.

Balancing Chemical Equations

Balancing chemical equations involves adjusting the coefficients of reactants and products so that the number of atoms for each element is equal on both sides of the reaction arrow. This ensures compliance with the law of conservation of mass and provides the correct proportions needed for the reaction to proceed, which is crucial in both laboratory and industrial settings.

Stoichiometry

Stoichiometry is the calculation of the quantities of reactants and products involved in a chemical reaction. It relies on the balanced chemical equation to determine the ratios in which substances react and are produced, allowing for accurate predictions and measurements in chemical processes.

Oxidation-Reduction Reactions

Oxidation-reduction (redox) reactions are processes in which electrons are transferred between substances, leading to changes in oxidation states. These reactions are critical in various applications, such as energy production, metallurgy, and chemical synthesis. Balancing redox reactions often involves additional steps to account for the electron transfer between species.

Transcript

00:01 This first reaction is already pretty clear that it is not balanced.

00:05 I have one on aluminum on the left, two on the right.

00:08 I don't even need to check the rest.

00:10 I already know the reaction is in balance.

00:12 So i'm going to start by balancing the aluminum, seeing where that takes me.

00:19 I see that i have, i'm going to put a two here in front of aluminum.

00:25 So now what i have on the left side is two of these.

00:29 If i set this to be two, then i'm going to put a one here as a place holder to make sure that i don't go back and mess with that one.

00:38 Okay.

00:40 So i have two aluminums on the left, two aluminums on the right, and since this aluminum is fixed, i next i'm going to look at the oxygen because i can't change how many of these i have at this point.

00:55 So if i have three oxygens on the right, that balances the three oxygens on the left.

01:01 So i'm going to say i have one of these here and now this coefficient is fixed i can't change it anymore and the only element i have left to change is the iron so to make the iron on the right balance i need two and that should have a total of two iron atoms on the right two on the left two aluminum on both sides and three oxygens on both sides next looking at b to check if it's balance i'm going to start with carbon it's the easiest element.

01:40 There are six carbon atoms on the left hand side, six carbon atoms on the right hand side, so the carbon checks out.

01:49 Hydrogen, i'm gonna check the hydrogens next because they only show up once on the left side.

01:55 Six times two means that there's 12 hydrogens on the left.

01:59 Here's there's 12 hydrogens on the right.

02:02 So the hydrogen also checks out.

02:05 And finally, for oxygen, take a look.

02:08 We have six times two is 12 oxygens here, and an additional six oxygens here.

02:21 So for the total of 18 oxygens on the left hand side, on this side we have six right here on the carbon compound, and an additional six times two is 12 on this side.

02:37 So for a total of also 18 oxygens.

02:40 So the oxygen also checks out, which means that this reaction is already balanced.

02:48 Balanced, and i don't have to do anything else.

02:53 Lastly, we have this big reaction involving a lot of reactants and products.

03:00 I'm just going to go from right to left to right.

03:03 I have one gold here, one gold here.

03:07 So the gold checks out.

03:10 For sodium, i have two sodium atoms.

03:13 On the left and on the right hand side i have so i have two nas on the left on the right hand side i have one here and three here so already i can see that my sodiums are not balanced and that means i need to fix the coefficients on this reaction so i would rather start from nothing i'm gonna erase all the coefficients that i was given because i think that is easier so i like to balance elements less and then things like water and carbon dioxide is second to last.

04:14 Because usually those are easier to fudge, so to speak, because they're by themselves.

04:21 So they're easier to use to account for any missing elements.

04:27 So that means if i'm using the elements last, i'm going to take a look first at my sodiums because all the sodiums are wrapped up in compounds.

04:36 So notice that we have one sodium here, one sodium here for a total of two sodiums on the right hand side.

04:45 So i'm going to say two here.

04:49 And if i'm saying that there are two sodium cyanides, then i'm saying that there must be one of each.

04:58 Of these compounds on the right.

05:00 So i can't change these coefficients anymore now that i fix them, which means that now i have to figure out how to account for everybody else using these elements.

05:09 So i'm going to go for water next because that's the compound that i have...

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