Stoichiometry Basic Introduction, Mole to Mole, Grams to Grams, Mole Ratio Practice Problems

Summary

This video provides a beginner-friendly introduction to stoichiometry in chemistry, focusing on three key types of conversions between substances in chemical reactions. It explains how to convert moles of one substance to moles, grams, or vice versa for another, using balanced chemical equations and molar ratios. The video walks through practical examples involving sulfur dioxide, oxygen, propane, and aluminum reactions. By the end, viewers will understand how to perform mole-to-mole, mole-to-gram, and gram-to-gram conversions, key skills for solving common stoichiometry problems.

Takeaways

• 🔍 The video introduces basic stoichiometry concepts, focusing on three main types of conversions: moles of one substance to moles of another, moles to grams, and grams to grams.
• 🧪 The first problem type involves converting moles of one reactant to moles of a product using the mole ratio from a balanced chemical equation.
• 📚 The second problem type requires converting moles of a reactant to grams of a product, which involves two steps: using the mole ratio and then the molar mass.
• ⚖️ The third problem type is a gram-to-gram conversion, which includes determining moles from grams using molar mass, applying the mole ratio, and then converting moles to grams of the product.
• 🔢 The video uses the example of sulfur dioxide reacting with oxygen to form sulfur trioxide to demonstrate the first type of conversion.
• ✅ A balanced chemical equation is essential before performing any stoichiometry calculations, as it provides the mole ratios needed for conversions.
• 📉 The video explains that converting moles to grams involves multiplying the number of moles by the molar mass of the substance.
• 🔝 The example of propane reacting with oxygen to form carbon dioxide and water is used to illustrate a two-step conversion process.
• 🌟 The video emphasizes the importance of practice in mastering stoichiometry problems, encouraging viewers to pause and try the problems themselves.
• 📊 The final example involves aluminum reacting with chlorine gas to form aluminum chloride, showcasing a three-step conversion process from grams to grams.

Q & A

What are the three types of conversions discussed in the video?

The three types of conversions discussed are: converting moles of substance A to moles of substance B, converting moles of substance A to grams of substance B, and converting grams of substance A to grams of substance B.

How do you convert moles of one substance to moles of another in a chemical reaction?

To convert moles of one substance to moles of another, you use the molar ratio from the balanced chemical equation and set up a proportion using the given amount of the first substance.

What is the molar ratio between sulfur dioxide (SO2) and sulfur trioxide (SO3) in the given example?

The molar ratio between sulfur dioxide (SO2) and sulfur trioxide (SO3) is 2:2, meaning two moles of SO2 produce two moles of SO3.

How many moles of oxygen gas will react completely with 4.7 moles of sulfur dioxide?

With a molar ratio of 2:1 between SO2 and O2, 4.7 moles of sulfur dioxide will react with 2.35 moles of oxygen gas.

What is the balanced chemical equation for the reaction between propane and oxygen to form carbon dioxide and water?

The balanced chemical equation is C3H8 + 5O2 → 3CO2 + 4H2O.

How do you convert grams of propane to grams of carbon dioxide?

First, convert grams of propane to moles using its molar mass, then use the molar ratio to find moles of CO2, and finally convert moles of CO2 to grams using the molar mass of CO2.

What is the molar mass of water (H2O) used in the video?

The molar mass of water (H2O) is 18.016 grams per mole.

How many moles of aluminum chloride will form if 35 grams of aluminum react with excess chlorine?

Using the molar mass of aluminum and the molar ratio from the balanced chemical equation, 35 grams of aluminum will produce 17.296 grams of aluminum chloride.

What is the balanced chemical equation for the reaction between aluminum and chlorine gas to form aluminum chloride?

The balanced chemical equation is 2Al + 3Cl2 → 2AlCl3.

How many grams of chlorine will react completely with 42.8 grams of aluminum?

Using the molar mass of aluminum and the molar ratio from the balanced chemical equation, 42.8 grams of aluminum will react with 168.75 grams of chlorine.

Outlines

00:00

🔍 Understanding Stoichiometry Basics

This paragraph introduces the fundamental concepts of stoichiometry in chemical reactions. It explains the three main types of conversions: moles of substance A to moles of substance B, moles of substance A to grams of substance B, and grams of substance A to grams of substance B. The focus is on understanding the molar ratio, which is crucial for these conversions. An example is provided where sulfur dioxide reacts with oxygen to form sulfur trioxide, and the process of balancing the chemical equation is detailed. The paragraph concludes with a step-by-step guide on how to calculate the moles of sulfur trioxide produced from a given amount of sulfur dioxide.

05:01

📚 Converting Moles to Grams in Chemical Reactions

This section delves into the process of converting moles of one substance to grams of another in chemical reactions. It uses propane reacting with oxygen to form carbon dioxide and water as an example. The paragraph outlines a two-step process: first, converting moles of propane to moles of carbon dioxide using the molar ratio, and second, converting moles of carbon dioxide to grams using the molar mass. The chemical equation is balanced, and the calculations are detailed, leading to the conclusion of how many grams of carbon dioxide are produced from a given amount of propane.

10:03

🔬 Advanced Stoichiometry: Grams to Moles Conversion

This paragraph continues the discussion on stoichiometry, focusing on converting grams of one substance to moles of another. It uses the reaction of propane with oxygen to produce carbon dioxide and water as an example. The process involves first converting grams of propane to moles using the molar mass of propane, then using the molar ratio to convert moles of propane to moles of water. The paragraph provides a detailed explanation of the calculations involved, including finding the molar mass of propane and using it to perform the conversion.

15:04

🧪 Balancing Chemical Equations and Conversions

This section introduces a new chemical reaction involving aluminum and chlorine gas to form aluminum chloride. It emphasizes the importance of balancing the chemical equation before performing stoichiometry calculations. The paragraph outlines the steps for converting grams of aluminum to grams of aluminum chloride, which includes converting grams to moles using the molar mass of aluminum, using the molar ratio to convert moles of aluminum to moles of aluminum chloride, and finally converting moles to grams using the molar mass of aluminum chloride.

20:05

📉 Comprehensive Stoichiometry Calculations

The final paragraph summarizes the stoichiometry calculations covered in the script. It reviews the process of converting moles to grams and grams to moles in the context of chemical reactions. The paragraph also highlights the importance of using molar ratios and molar masses in these conversions. An example is given where aluminum reacts with chlorine gas, and the calculations for converting grams of aluminum to grams of chlorine are detailed. The paragraph concludes with a reminder of the steps involved in these conversions and encourages practice to master stoichiometry problems.

Keywords

💡Mole Ratio

The mole ratio is a fundamental concept in stoichiometry that describes the relationship between the amounts of reactants and products in a balanced chemical equation. It is used to predict how many moles of one substance will react with or produce moles of another in a chemical reaction. In the video, the mole ratio is used to convert moles of one substance to moles of another, such as converting moles of sulfur dioxide to moles of sulfur trioxide in the reaction SO2 + O2 → SO3.

💡Molar Mass

Molar mass is the mass of one mole of a substance, measured in grams per mole (g/mol). It is calculated by summing the atomic masses of all the atoms in a molecule or formula unit of a substance. In the video, molar mass is used to convert between grams and moles of a substance, which is essential for solving stoichiometry problems. For instance, the molar mass of carbon dioxide (CO2) is used to convert moles of CO2 to grams in the propane combustion reaction.

💡Balanced Chemical Equation

A balanced chemical equation is a chemical equation in which the number of atoms for each element is the same on both sides of the equation, indicating that the law of conservation of mass is obeyed. Balancing equations is crucial for accurate stoichiometric calculations. In the script, the video demonstrates how to balance equations for reactions involving sulfur dioxide, propane, and aluminum.

💡Stoichiometry

Stoichiometry is the calculation of reactants and products in chemical reactions based on the balanced chemical equation. It is used to determine the quantities of substances involved in reactions. The video focuses on stoichiometry problems, teaching viewers how to convert between different units (moles, grams) and substances using the concepts of mole ratio and molar mass.

💡Conversion Factors

Conversion factors are used to change the units of a measurement. In chemistry, they are often used to convert between grams and moles or between different substances based on their mole ratios. The video script provides examples of using conversion factors to solve stoichiometry problems, such as converting grams of propane to moles of carbon dioxide.

💡Atomic Mass

Atomic mass is the mass of an individual atom, usually expressed in atomic mass units (amu). It is used to calculate the molar mass of a substance. In the video, atomic masses of elements like sulfur, oxygen, carbon, and hydrogen are used to determine the molar masses of compounds like sulfur dioxide, carbon dioxide, and water.

💡Chemical Reaction

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. The video discusses various chemical reactions, such as the reaction of sulfur dioxide with oxygen to form sulfur trioxide, and the combustion of propane with oxygen to produce carbon dioxide and water.

💡Excess Reactant

An excess reactant is a reactant that is present in amounts greater than needed for the reaction to go to completion. In the context of the video, 'excess oxygen gas' means that all of another reactant, like sulfur dioxide, will react completely, and the amount of oxygen used can be calculated based on the stoichiometry of the balanced equation.

💡Gram to Gram Conversion

A gram to gram conversion is a type of stoichiometry problem where the goal is to convert the mass of one substance to the mass of another substance. The video explains how to perform such conversions using a three-step process involving molar mass and mole ratios, as demonstrated in the reaction of aluminum with chlorine gas.

💡Diatomic Molecules

Diatomic molecules are molecules consisting of two atoms, typically of the same element, joined by a covalent bond. In the video, oxygen (O2) and chlorine (Cl2) are mentioned as diatomic molecules. Understanding their diatomic nature is important for balancing chemical equations and performing stoichiometry calculations.

Highlights

Introduction to stoichiometry and chemical conversions

Three types of conversions in chemical reactions: moles to moles, moles to grams, and grams to grams

Conversion of moles of substance A to moles of substance B using molar ratios

Example problem: Sulfur dioxide reacts with oxygen to form sulfur trioxide

Balancing chemical equations is crucial before performing conversions

Using molar ratios to convert moles of SO2 to moles of SO3

Conversion of moles of propane to grams of CO2 in a combustion reaction

Two-step process for converting moles to grams: molar ratio followed by molar mass

Example problem: Propane reacts with oxygen to form carbon dioxide and water

Calculating grams of CO2 produced from moles of propane

Conversion of grams of propane to moles of oxygen using stoichiometry

Molar mass of substances is essential for converting between moles and grams

Example problem: Aluminum reacts with chlorine gas to form aluminum chloride

Three-step process for converting grams to grams in a chemical reaction

Balancing the chemical equation for aluminum and chlorine gas reaction

Calculating grams of aluminum chloride from grams of aluminum

Understanding molar mass and molar ratios for problem-solving in chemistry

Practical applications of stoichiometry in chemistry problems

Transcripts

this video will provide a basic

introduction into story

geometry and for most chemical reactions

there's basically three types of

conversions that you need to concern

yourself with the first type the

shortest one is to convert the moles of

substance a to the moles of substance B

and you need to identify the mol ratio

in order to do

that number one is going to focus on

that problem the second type of problem

is to convert the moles of substance a

to the G of substance b or you could be

given the grams of substance a and you

need to convert it to the moles of

substance B so that's the second type of

problem that you'll

see the third type is if you're given

the grams of substance a and you need it

to convert to the grams of substance

B so this involves I believe three steps

and this one two steps and the first one

is a single

step so let's begin working on these

problems number one sulfur dioxide

reacts with oxygen gas to form sulfur

trioxide if 3.4 moles of sulfur dioxide

reacts with excess oxygen gas how many

moles of sulfur trioxide will form

form the first thing that we need to do

is we need to write a balanced chemical

equation sulur dioxide is

SO2 oxygen is diatomic it's O2 and

sulfur trioxide is s

SO3 so now we need to balance

it the sulfur atoms are balanced on both

sides but we have four oxygen atoms on

the left and three on the right so let's

start by putting two in front of2 so now

we have two sulfur atoms which means we

need to put a two in front

of3 now it turns out that the number of

oxygen atoms on both sides is now six on

this side 2 * 3 is six here 2 * 2 is 4

plus another two that's six so we have a

balanced chemical equation at this

point now we're given 3.4 moles of

sulfur

dioxide

and we want

to convert it to the moles of sulfur

trioxide so what we need to do is use

something called a mol

ratio the M ratio between sulfur dioxide

and sulfur trioxide is 2

to2 so what this means is that for every

two moles of sulfur dioxide that reacts

two moles of sulfur trioxide will be

produced now since we have moles of2 on

the top left we need to put that on the

bottom

right so that those units will

cancel and the other two moles of SO3 we

could put that on

top so whenever you want to convert from

the moles of substance a to the moles of

substance B all you need is one

additional fraction beyond what you're

starting

with and you'll get the answer 2 / 2 is

basically one so the answer is

3.4 since the M ratio the coefficients

are the same the M ratio is

one and so this is the answer for part

A based on this example go ahead and try

Part

B how many moles of oxygen gas will

react completely with 4.7 moles of

sulfur

dioxide

so let's start with what we're given

which is 4.7 moles of

SO2 now we need to convert the moles of

SO2 to the moles of oxygen

gas so it's a one-step problem all we

need is one additional

fraction so we need the M ratio between

SO2 and O2 so for every two moles of SO2

that reacts

one Mo of oxygen gas reacts along with

it so let's put the two moles of SO2 on

the bottom but on the top we're going to

put one mole of o2 based on the

coefficient in front of it so make sure

you balance the chemical equation before

starting this

problem so the answer is going to be 4.7

divid 2 which is uh

2.35 moles of o2

as you can see it's not that difficult

to convert from the moles of one

substance into the moles of another

substance number two propane reacts with

oxygen gas to form carbon dioxide and

water part A if 2.8 moles of propane

reacts with excess oxygen gas how many

GRS of CO2 will form so let's write down

what we need to do we're given the moles

of propane C3

h8 and we need to convert it to the gr

of carbon dioxide so basically we have

the moles of substance a and we want it

to convert it to the gr of substance B

so it's a two-step process so let's take

it one step at a time so starting with

the moles of a you want to use the M

ratio to change it to a different

substance while keeping the unit the

same the unit is moles the substance is

a so you want to change one thing at a

time in this first step we're changing

from substance a to substance B now that

we have substance B we could change the

unit from moles to

gr so it's a two-step process for this

problem now before we can

begin let's write a balanced chemical

equation so we have propane C3 h it

reacts with oxygen gas to produce carbon

dioxide and

water so we have three carbon atoms on

the left therefore we need to put a

three in front of

CO2 and there are eight hydrogen atoms

on the left and two on the right 2 * 4

is eight so let's put a four in front of

water now 3 * 2 is six so we got six

oxygen atoms from the 3 CO2 molecules

and 4 * 1 is four so we have four oxygen

atoms from the four water molecules

giving us a total of 10 oxygen atoms on

the right side which means we need 10 on

the left 10 / 2 is 5 so therefore we

need to put a five in front of o2 so now

we have a balanced chemical

equation now in part A we're given

2.8 moles of

propane so first we need to convert or

change the substance from propane to

carbon dioxide because that's what we're

looking for so let's use the M ratio to

change the

substance so the M ratio between propane

and carbon dioxide it's 1 to

3 so for each mole of propane that

reacts 3 moles of CO2 will be produced

in this

reaction so we could cancel these

units now we can convert from moles of

CO2 to G of CO2 so we need the M mass of

carbon dioxide so CO2 contains one

carbon and two oxygen atoms so that's

12.01 + 2 *

16 which is going to be 4

24.01 so 1 mole of CO2 has a mass of

44.1

G so whenever you see this number the M

Mass the units are G per

mole so one mole of that substance has a

mass of 44

G so now let's just do the

math so we can multiply across it's 2.8

* 3 * 44.0 0

1 and so I got

369.50 gram of carbon

dioxide so that's it for part A now

let's move on to Part B feel free to

pause the video if you want to try it

it's very similar to part

A how many GRS of oxygen gas will

completely react with 3.8 M of

propane so we need to convert moles of

propane ultimately to G of oxygen so

we're going to follow the same steps

first we need to change the substance

from propane to oxygen but keeping the

unit the same so we need to use the M

ratio to change a substance after that

we could use the M Mass to convert from

moles of o2 to G of

o2 so that's the blueprint of what we

need to

follow so let's start with what we're

given that is 3.8 moles of

propane and let's use the M ratio to

convert it to moles of o2 to change a

substance so the M ratio is 1 to

5 so one mole of propane C3 h8 will

react completely with five moles of

o2 so now we're at this point so we need

to use the M Mass to go from moles to

G now the atomic mass of a single oxygen

atom is 16 so the M mass of an oxygen

molecule that has two oxygen atoms is 2

* 16 or 32 so so it's 32 G per

mole so what that means is that 1 mole

of o2 contains a mass of 32

G now we can get the answer so it's 3.8

* 5 *

32 and so it's

68 G of

o2 so that's the answer for Part B

now let's move on to part C if 25 G of

C3 h8 reacts with excess oxygen how many

moles of water will

form so this time we're given the gr of

C3

h8 and we need to convert it to the

moles of water

so we're given the grams of substance a

and we need to convert it to the moles

of substance B so first we need to

change the unit we need to go from GRS

to moles and we're going to use the M

Mass to do so and then we're going to

use the M ratio to change the substance

from A to B so in our particular example

we're going to convert the GRS of

propane to the moles of propane using

the M mass of propane and then we'll use

the M ratio to change the substance from

propane to water so basically part C is

the reverse of A and

B so let's begin let's start with what

was given to us in the problem that is

25 G of

propane now we need to find the M mass

of propane it has three carbons and

eight

hydrogens so that's 3 *

12.01

Plus 8 *

1.8 so that works out to be

44.94 G per

mole so one mole of

propane has a mass of

44.0 94

grams so we could cancel the unit GRS of

C3 H so now let's use the M ratio to

change the substance from propane to

water so the mol ratio is 1 to

4 so for each mole of propane that

reacts four moles of water

will be

produced now let's perform the operation

it's

25 /

44.94 *

4 so this is about

2.27 moles of H2O and that's the

answer

Part D if 38 G of water are produced in

the reaction how many moles of CO2 were

produced so this time we're given the gr

of water and we need to find the moles

of carbon dioxide so just like before

first we're going to change the unit

from gr to moles using the M Mass and

then using the molar ratio we're going

to change a substance from water to

CO2 so let's begin if you want to pause

the video and work on this problem feel

free go ahead because the best way to

learn is through practice by taking

action so let's start with 38 G of

H2O and let's convert it to

moles so we need to find a m mass of

water so we have two hydrogen atoms plus

an oxygen atom each hydrogen atom is

1.8 we got to times that by two and then

add 16 to

it so the M mass of water is

18.016 G per mole so one mole of water

has a mass of 18.016

G so now we can move on to our last step

and that is converted moles of

water

to moles of CO2 so the mol ratio is 3 to

4 so for every four moles of water that

are produced in this reaction three

moles of carbon dioxide are produced

along with

it so it's going to be 38 /

18.016 multiplied 3 / 4 so the answer

that I have

have is

1.58 moles of carbon

dioxide and that's the final

answer number three aluminum reacts with

chlorine gas to form aluminum chloride

part A if 35 G of aluminum reacts with

excess chlorine how many grams of

aluminum chloride will

form let's start with reaction so we

have aluminum reacting with chlorine gas

chlorine is diatomic just like oxygen

gas and when combined it's going to form

aluminum chloride now we need to write

the formula of aluminum

chloride how can we do so aluminum has a

positive3 charge chloride has a minus

one

charge so using the crisscross method

it's going to be al1 cl3 or simply Al

cl3 now before we begin the problem we

need to balance the chemical

equation the number of chlorine atoms is

not the same on both

sides but the number of aluminum atoms

they're equal on both sides so we got

two on the left three on the right what

I like to do is find the least common

multiple of two and three or just

multiply two and three which is six so

to make them equal I need six chlorine

atoms on both sides sides so I'm going

to put a three in front of cl2 that's

going to give me six and a two in front

of

al3 so now I have six chlorine atoms but

I now have two aluminum atoms on the

right side so I got to put a two on the

left so now we could focus on part

A if 35 gr of aluminum reacts with

excess chlorine how many gr of aluminum

chloride will form so this is a gram to

G conversion we need to convert the gr

of substance a to the G of substance

B now there are three steps that we need

to perform to complete this process

first we need to change the units from

grams to moles so we need to go from GRS

of a to moles of substance a and we need

to use the mol mass of substance a to do

that next once we have the moles we need

to change from substance a to substance

B so we need to use the M ratio for that

part finally now that we have the moles

we need to change the unit from moles to

G using the molar mass of substance

B so there are three steps that we need

to take this is step one step two step

three so in our particular example we

have the GRS of

aluminum and we need to convert it to

the moles of aluminum now X we're going

to use the M ratio to convert it to the

moles

of I'm looking at the wrong

problem part A we still have the grams

of aluminum but we need to convert it to

aluminum chloride so we got to get the

moles of alcl3 and

x and then finally we can convert that

to the grams of aluminum

chloride so that's an overview of what

we need to do in this

problem

so let's start with what we're given

that is 35 G of

aluminum based on a periodic table the

atomic mass of aluminum is

26.98 so that means 1 Mo of

aluminum has a mass of

26.98

G next we need to change the substance

from aluminum to aluminum chloride so

the M ratio is 2

to2 so for every two moles of Al that

reacts 2 moles of aluminum chloride will

be

produced now the last thing that we need

to do is we need to change from the

moles of al3 to G so we got to find the

M mass of al3 so we need to add the at

atomic mass of one aluminum atom with

three chlorine atoms so this is

26.98 + 3 times the atomic mass of

chlorine which is

35.45 so this is equal to

133 33 G per

mole so 133 .33 G of

al3 is equivalent to 1 Mo of

al3 so now let's do the math it's 35 /

26.98 2 over 2 is 1 so we could cancel

the twos if we want to and then let's

multiply by

133.33

so the final

answer is

17296 G of aluminum chloride so that's

the answer for part

A Part B how many GRS of chlorine will

react completely with 42.8 G of aluminum

so feel free to try that

problem so we have the grams of aluminum

next we need to change it to the moles

of aluminum and then we're going to

change a substance using M ratio to

moles of chlorine and then finally well

chlorine diatomic so this is cl2 next

we'll change it to the grams of

chlorine so that's a gr

conversion so let's start with

42.8 g of

aluminum and let's convert it to moles

using the same atomic mass which is

26.98 now let's use the M ratio to

change it from aluminum to cl2 so it's

2: 3 so for every two moles of aluminum

that reacts three moles of chlorine gas

reacts with

it now we need to find the M mass of cl2

it's going to be

35.45 * 2 which is

70.9 so one mole of

cl2 is equivalent to 70.9

G so always make sure the other units

cancel out if they don't then there's a

mistake somewhere

so now let's finish the problem it's

42.8 /

26.98 multiplied 3 /

2 and then multiplied by

70.9 so the final answer that I have is

168.75

you know how to perform a mleo mo

conversion which we covered in problem

one you know how to go from the moles of

one substance to the grams of another or

the grams of one substance to the moles

of a different substance and you know

how to perform a gram to gram conversion

as well so these are common stochiometry

problems that you might see in a typical

chemistry class so thanks for watching

and have a good

day

e