The following diagram represents the reaction of A2 (red spheres) with B2 (blue spheres): (a) Wr

The following diagram represents the reaction of A2 (red...

The following diagram represents the reaction of $\mathrm{A}_{2}$ (red spheres) with $\mathrm{B}_{2}$ (blue spheres): (a) Write a balanced equation for the reaction, and identify the limiting reactant. (b) How many moles of product can be made from 1.0 $\mathrm{mol}$ of $\mathrm{A}_{2}$ and 1.0 $\mathrm{mol}$ of $\mathrm{B}_{2} ?$

The following diagram represents the reaction of $\mathrm{A}_{2}$ (red spheres) with $\mathrm{B}_{2}$ (blue spheres):
(a) Write a balanced equation for the reaction, and identify the limiting reactant.
(b) How many moles of product can be made from 1.0 $\mathrm{mol}$ of $\mathrm{A}_{2}$ and 1.0 $\mathrm{mol}$ of $\mathrm{B}_{2} ?$

Key Concepts

Balanced Chemical Equations

A balanced chemical equation represents the conservation of atoms by ensuring that the same number of each type of atom appears on both sides of the reaction. It provides the basis for quantitative analysis in chemical reactions by establishing the exact stoichiometric relationships between reactants and products.

Stoichiometry

Stoichiometry involves the calculation of reactants and products in a chemical reaction using the mole ratio derived from the balanced chemical equation. It is central to predicting theoretical yields, comparing quantities, and performing conversions between moles, mass, or number of particles.

Limiting Reactant

The limiting reactant is the substance that is entirely consumed first during a chemical reaction, thereby limiting the amount of product formed. Identifying the limiting reactant is essential in determining the maximum yield of the reaction and is based on the initial amounts and stoichiometric coefficients from the balanced equation.

Transcript

00:01 We're asked first to write the balance equation for the reaction using the fact that the red spheres are a2.

00:11 We've got a2 in red and b2 in blue.

00:18 So we're going to start off making this really easy, just literally counting how many of each particle we have in what i'm going to call the before box.

00:29 Okay, so we've got four a -2s and six b -2s.

00:38 And then in our after box, after meaning, of course, after the reaction takes place, we see we have two different kinds of particles.

00:47 We've got this new particle that seems to have one a and three b's, and we still have some a2 left.

01:05 So counting these up, there's four of these and two of those.

01:11 And while this describes exactly the contents of the before and the after containers, they don't describe the chemical equation.

01:22 Now a chemical equation tells us two things.

01:29 It describes the changes that took place, and it does so using simplest whole number ratios.

01:42 So if we take a look, even though this equation perfectly represents the contents of the boxes, it is not a good equation because it includes some reactants on the product side, essentially unreacted reactants.

02:01 So we're going to treat this a little bit like an algebraic equation, and we're going to eliminate what i would call these spectator molecules.

02:10 They don't actually participate in the reaction.

02:14 They're just watching around.

02:17 So when i do that, i see that i'm left with 2a2 plus 6b2 yields 4ab3.

02:31 And even then, i'm still not done because remember that chemical equation used the simplest whole number ratio.

02:38 We're saying right now that two of these with six of these makes four of those, but those are not the simplest ratios.

02:46 We notice that each of these coefficients can be divided by two.

02:54 So we can simplify these ratios further and write a2 plus 3b2 yields 2 ab3.

03:06 Now what we have is an equation that describes just the changes, none of the spectators, and does so using lowest whole number ratios.

03:17 So this is our chemical equation.

03:19 We're also asked to find which is the limiting reactants.

03:25 Remember that the limiting reactant is the reactant that runs out first and determines how much product is made.

03:37 We see in this box that we had some leftover, some excess a2.

03:45 So this is excess reactants.

03:48 It was present in the before and the after.

03:51 That's the piece that we subtracted from our equation.

03:55 So if 02 is the, not o2, i apologize, if a2 is the excess reactant, that means that b2 was the limiting reactant...

Please give Ace some feedback