## Mole and How to Use the Mole in Chemistry

how do mr. Casas here coming to you from

beautiful task exceeded Texas and today

we're going to talk about the mold and

what's important about the mole is that

you learn what it can do you need to

understand the mold because it's a big

part of what we do in stochiometry and

much of the advanced chemistry so you

need to learn the mole you're going to

need a periodic table and you're going

to need a calculator for today's lesson

here are some assumptions I'm going to

make one that you're familiar with the

periodic table that you know how to use

a calculator that you can perform unit

conversions and you're familiar with

atomic masses so why the mole

well the mole was constructed so that

scientists or chemists in particular

would have a way to count atoms ions and

molecules without having to count them

individually they could do it by using

mass they could weigh out certain

amounts and by using the mole they would

know how much they had or how many they

had and it's because atoms and molecules

are really small so we can't count them

individually so we came up with a mole

now if you want to know what the mole is

really all about go watch one of my

mole but right here I don't want to go

through the history I just want you to

understand what a mole is and how to use

it so what's a mole a mole is an avocado

number of anything and Avogadro's number

is six point zero to two times 10 to the

23 that's an important number and that's

what a mole is and a mole is just a

number like a dozen is 12 or a pair is

two a mole is six point zero to two

times 10 to the 23 which is a humongous

number but that's because atoms are so

small

let's move on what is molar mass well

molar mass is an element or a mole of an

element is the numeric equivalent of the

atomic mass but in grams so the molar

mass is the atomic mass in grams a molar

mass is the mass of six point zero two

two times ten to the 23 particles no

matter what the particle is bigger

particles more grams smaller particles

fewer grams so hydrogen is one point

zero one atomic mass units one mole of

hydrogen is one point zero one grams or

carbon is twelve point zero one atomic

mass units and one mole of carbon is

12.01 grams the mole of an element is

the numeric equivalent of the atomic

mass in grams what about the molar mass

of a compound

well if elements make up compounds then

all we have to do is add up the atomic

masses of the different elements in the

compound and is the numeric equivalent

of that in grams water is eighteen point

zero two atomic mass units therefore one

mole of water would be eighteen point

zero two grams carbon dioxide equals

forty four point zero one atomic mass

units therefore one mole of carbon

dioxide is forty four point zero one

grams all right let's look at some

conversions it's not important for you

to understand the history as much as it

is that you understand how a mole is

used and one mole is 6.02 times 10 to

the 23 particles and 6.022 times 10 to

the 23 particles is

one mole and particles can be atoms it

can be ions it can be molecules it can

be formula units but these conversions

are used to go from moles to particles

or particles to moles

let's do an example how many atoms are

in 1.5 moles of gold well I'll take 1.5

moles multiply it by the conversion of

6.0 to 2 times 10 to the 23 atoms per

mole I know that I've got it set up

right because moles cancel out I'm going

to plug and chug into my calculator and

I get 9 point zero 3 times 10 to the 23

atoms of gold in 1.50 moles now in this

conversion we have moles per grams or

grams per moles and we use this

conversion to go between the macro rule

in the micro rule and the subatomic

world and so moles per grams very

important conversion so let's look at an

example I'll go to my periodic table and

let's pick oxygen and oxygen is 16 point

zero zero grams and therefore one mole

or 16 point zero zero grams of oxygen is

one mole oxygen and one mole of oxygen

is 16 point zero zero grams of oxygen

and with that knowledge that we can get

from the periodic table we can use to

convert from molecules to moles to grams

or grams to moles to molecules here's an

example how many moles are in 29.5 eight

grams of carbon well 29.5 eight grams I

know that I want to take the grams I

want to change it to moles therefore I'm

going to use molar mass go to my

periodic table and there's carbon which

is going to be twelve point zero one per

mole

and I've got it set up so that my grams

cancel out put it in in plug and chug

and I get two point four six three moles

of carbon let's look at another example

how many atoms in five point two one

grams of sulfur there's my grams now

want change two atoms so I'm going to

have to go two moles and then particles

there's no direct way from grams to

particles but I can go from grams to

moles to particles so I'll go to my

periodic table get my molar mass and

sulfur is 32 point zero seven grams I

know I have it set up right because

grams cancel out and then I'm going to

take and multiply by the number of atoms

in one mole remember mole is just a

number so it doesn't matter what I have

as long as I remember that a mole is six

point zero two two times 10 to the 23

atoms and small sulfur cancels out and

I'm going to plug and chug and I get

nine point seven eight times ten to the

twenty two atoms sulfur that's a huge

number

all right let's recap a mole is just a

number like a dozen which is twelve a

mole equals six point zero two two times

10 to the 23 of anything and molar mass

is the numeric equivalent of the atomic

mass in grams and the reason that's

possible you can find out in one of my

other videos so check out your chem

coach comm and subscribe to my You Tube

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