Aluminum reacts with sulfur gas to form aluminum sulfide....

Name: Problem 74, Chapter 3: Chemistry - Principles and Reactions
Uploaded: 2023-08-04T21:29:56-08:00
Duration: 7 min 29 s
Channel: Andrija Isakov
Description: Aluminum reacts with sulfur gas to form aluminum sulfide. Initially, 1.18 mol of aluminum and 2.25 mol of sulfur are combined. (a) Write a balanced equation for the reaction. (b) What is the limiting reactant? (c) What is the theoretical yield of aluminum sulfide in moles? (d) How many moles of excess reactant remain unreacted?

Aluminum reacts with sulfur gas to form aluminum sulfide. Initially, 1.18 mol of aluminum and 2.25 mol of sulfur are combined. (a) Write a balanced equation for the reaction. (b) What is the limiting reactant? (c) What is the theoretical yield of aluminum sulfide in moles? (d) How many moles of excess reactant remain unreacted?

Aluminum reacts with sulfur gas to form aluminum sulfide. Initially, 1.18 mol of aluminum and 2.25 mol of sulfur are combined.
(a) Write a balanced equation for the reaction.
(b) What is the limiting reactant?
(c) What is the theoretical yield of aluminum sulfide in moles?
(d) How many moles of excess reactant remain unreacted?

Key Concepts

Theoretical Yield

The theoretical yield is the maximum amount of product that can be produced from a given amount of limiting reactant according to the balanced chemical equation. This concept is fundamental in calculating the efficiency of a reaction and determining how much product can be expected under ideal conditions.

Excess Reactant

An excess reactant is the reactant that remains after the reaction has completed, due to it being present in greater quantity than what is required by the stoichiometric ratios of the balanced equation. Calculating the amount of excess reactant remaining helps in understanding the reaction's dynamics and resource utilization.

Balanced Chemical Equation

A balanced chemical equation shows the reactants and products with equal numbers of atoms of each element on both sides of the reaction arrow. It is crucial in stoichiometry, as it provides the molar ratios needed to determine how much of each substance is involved in the reaction.

Limiting Reactant

The limiting reactant is the reactant that is completely consumed first in a chemical reaction, thus determining the maximum amount of product that can be formed. It is identified by comparing the mole ratios of the reactants to the ratios required by the balanced chemical equation.

Transcript

00:01 In this question, we're given a chemical reaction between aluminum and sulfur producing aluminum sulfide.

00:11 We have 1 .18 moles of aluminum and 2 .25 moles of sulfur gas.

00:19 Now, in part a, we are asked to write a balanced chemical equation.

00:24 In part b, we're asked what the limiting reactant is.

00:28 In c, we want to find what the theoretical yield of the product is in moles.

00:35 And finally, in part d, we're asked to find the number of moles of the excess unreacted reactant.

00:50 So, let's get started.

00:56 First of all, our balanced chemical equation.

01:06 We know that aluminum and sulfur...

01:08 Well, aluminum in its pure form is just a single atom of aluminum, and sulfur as a gas is a single atom of sulfur.

01:25 As a solid, it would be a group of 8.

01:31 But in this case, it's not.

01:36 Then, aluminum sulfide, from the chemical formula, using the ionic compound naming system, we can tell that aluminum sulfide contains aluminum and sulfur, and just those.

01:57 Now, sulfur, if you consult your periodic table, is located at the third last row, or the third last column, rather.

02:10 And so, it has a full valence shell when it gains 2 electrons.

02:14 So, its stable charge is negative 2.

02:20 Aluminum, on the other hand, is in group 13, or the 13th column.

02:29 And so, as we might expect, has a full valence shell when it loses 3 electrons.

02:35 And so, it has a stable ion charge of 3+.

02:42 And thus, using a little cross rule, or whatever you call it, we get that aluminum sulfide has the formula al2s3.

02:58 And then, in order to balance this equation, we need 3 sulfurs on the right side as well, as well as 2 aluminums.

03:09 And that's part a.

03:13 Now, for part b, we have to consider our amounts in moles.

03:18 So, the limiting reactant will be the reactant that would theoretically be all used up if we used as much of these amounts as we can for the reaction...

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