Hi. This is Mr. Andersen and

today I’m going to show you how to do mole conversions. Sometimes we call these mole

gram conversions. But the first thing kids get confused by is just the word mole. I know

it’s a furry animal, but the mole comes from the word molecule or the root molecule. And

so if you think of it like that, that’s an easier way to kind of get at it. Why do we

even use it? Well the reason we use mole is the mole allows you to deal with chemistry.

It allows you to deal with atoms that are really really small in the laboratory. And

so the nice thing about a mole is it gives you a usable amount. You can kind of think

of it that way. Another way to think about a mole is it’s simply a unit. And so if I

say I need a dozen eggs, you’re not scared of the word dozen. It’s not very scary. And

you shouldn’t be scared of the word mole. All it is is 6.022 times 10 to the 23rd. So

it’s a number. And so by the time you’re done with this you should be able to take the amount

of water inside this beaker, it looks like we have about 200 ml and thereby 200 grams

of water. And you should be able to figure out how many molecules of water are actually

in that. So let’s get to it. Let’s start by talking about eggs. And so a dozen is simply

the number of eggs. And so if you have a dozen eggs you know that one dozen is equal to 12

eggs. And so when you’re dealing with a mole, it’s the same way. It’s just going to be a

number of atoms or particles that you have. Also you might know that a dozen eggs weighs

24 ounces. And I didn’t know that but I learned this while making this. If you get large eggs

at the supermarket, large means that every dozen eggs weighs 24 ounces. And if you go

to extra large that’s 27 ounces. So if you’re getting Grade A Large Eggs, if you take a

dozen of those that’s going to be exactly 24 ounces. And so what we could do, you should

be able to do this in your head, is you should be able to go from eggs to dozen to ounces.

In other words if I have a dozen eggs. How many eggs do I have? Well you’d simply multiply

this times 12, when you run in this direction. And if I have one egg, how many dozen do I

have? Well you’re going to divide by 12 as you go in the other direction. And likewise

if you had a dozen eggs, weighs 24 ounces, you simply are going to take it times 24 to

figure out how many ounces you have. And thereby as you move back you’re going to divide by

24. And so if you think about this example when you start talking about moles the next

slide shouldn’t be scary at all. If I were to say to you, let’s say I have 48 ounces

of eggs, how many eggs do I have? You should be able to figure out that that’s 24 eggs.

Okay. So let’s go to the next slide and you’ll see that it’s not really going to change.

So what is a mole? A mole is simply a number. And so it’s 6.022×10^23 particles. The other

thing that you need to know is how much a mole actually weighs. To figure out the mass,

just like we said one dozen eggs weighs 24 ounces, 1 mole always weighs the formula mass.

And so if we’re dealing with H2O for example, how do I figure out how much a mole of water

weighs? You’re going to have to figure out, as I make my H correctly, you’re going to

have to figure out the molecular mass or the formula mass of that. And so let’s go forward

for a second. So if we’re on this screen right here, I have to figure out H2O and its formula

mass. To do that well, H2O has 2 Hs. So you’ve got 1 H, 2 Hs. And then 1 oxygen. And so on

the periodic table you’re going to find the mass of each of those. So here is hydrogen.

And so it has a mass of 1.01. The other hydrogen has a mass of 1.01. And then the oxygen which

is way over here has a mass of 16.00. And so if I add all of those masses up, the mass

of water is going to 18.02. And so if we want to say how much mass does one mole of water

have? It’s going to be 18.02 grams. And so you’ll have to do this if you’re ever going

from moles to grams. You’ll have to get a periodic table out. And you’re going to have

to figure out what’s the formula mass of that. And so let’s go back to this then. So just

like we could go from one egg to the dozens to the ounces of eggs we can go from particles,

and that could be either atoms or molecules to moles and then finally to grams. One mole

is going to have exactly 6.022 x10^23 particles. And so if you wanted to go from moles to particles

you’d simply multiply it times 6.022×10^23. Just like we did with a dozen eggs. And thereby

if you want to go from particles back to moles, then we’re going to have to divide. And if

we want to go from moles to grams we’re going to have to multiply it times the formula mass

or the mass of that molecule or atom. And then if we want to go back we’re going to

divide it. And so those two strategies allow you to make these kind of work. But I always

want you to understand how to do this using factor-label method. And if you don’t know

how to do that then make sure you look at the video on how to do factor-label. So let’s

do some actual problems, because that’s what you want to know how to solve. And so let’s

say we have this. Convert 0.200 moles of H2SO4 to grams. And so if I go back and figure out

where am I going to go, well right here they’re telling me I’ve got moles and I want to get

all the way to grams. And so which one of these am I going to use? We’re going to use

this first conversion. It’s where one mole is equal to the formula mass. We’re going

to use that conversion right here. So let’s go forward. So if you’re ever doing factor-label

I always tell you remember write .200 moles over 1. And now I’m just going to multiply

it times a factor. So I want to get rid of the moles so I’m going to put 1 mole on the

bottom. And then I want to get to grams is my goal. And so I’m going to get to grams

on the top. So I want to find that conversion between moles and grams. And remember 1 mole

of anything is the atomic or the formula mass of that. And so we have to figure out H2SO4.

So let’s go find that. So H2SO4 as I find my periodic table and let’s switch colors,

H2SO4 is going to have 2 hydrogens. And so there’s two of these 1.01. So that’s going

to be 2 x 1.01 which is equal to 2.02. Also in H2SO4, let’s write that down here, H2SO4,

we’ve got 1 sulfur. So I find sulfur on here. Sulfur has a mass on 32.06. And then we’ve

got to figure out, I’ve got 4 oxygens. So it’s O4. So I’m going to take 4 times oxygen,

and oxygen is 16. And so 4 times 16 is 64. So I have to add all of these up. So I’m going

to take this, 2 excuse me. This is an 8. This is a 0. This is a point. And this is 96, 98.08.

So this is the formula mass of H2SO4. And so once I’ve got that let’s go to where our

actual problem is. So we’ve got 98., let me go back. I forgot it. 98.08. So I have 98.08

grams in one mole of, this is sulfuric acid. So now I just, I’m going to multiply that.

So I’m going to cross off my moles. Get rid of my moles. And so now I’ve gotten to grams.

And so now if you look at it I’m just going to take 0.200 times 98.08. So let me grab

a calculator. So that’s going to be 0.2 times 98.08 and I get 19.616. So let me go back

to the presentation. 19.616. And so it’s 19.616 grams of H2SO4. Okay. Now let’s do significant

digits. This has how many significant digits? 3. And so this would not be the correct answer.

The correct answer would be 19.6 grams of H2SO4. So that’s going from moles to grams.

And we just simply multiplied it by the number of grams. Okay. Let’s go to a little bit harder

one. This one we’re going to take 102.8 grams of water and then were going to figure out

how many molecules that is. So if we go back to our little chart, they’re telling us now

how many grams we have. And we have to go all the way over here to particles. And so

I’m going to have to use both of these conversions. This conversion is going to get me from grams

to moles. And then this conversion is going to get me to the actual number of particles.

So let’s take a stab at that. Here we go. So first thing I’m going to do is I’m going

to write out what I start with. That’s 102.8 grams. And I’m going to put that over 1. This

is H2O. Now I’m going to multiply that, so I’m going to multiply that times, I’m going

to put grams of H2O on the bottom. Because I want to get rid of that. And I always have

to go the mole. Mole is always going to be in the middle. So I’m going to put moles on

the top. I know 1 mole, and we’ve already done the water one, H2O, we already said that

that is 18.02 grams of water. So now my grams of water would cross out. Now the next thing

I want to do is I want to go from here, from moles to molecules. So what’s my conversion

to do that? 1 mole of anything is always Avogadro’s number, so 6.022×10^23 of molecules. And so

now my moles will cross and I love factor label because you can always look through

and make sure, yep, I’m getting to molecules and that’s what the question is trying to

ask. And so if we do that on the calculator, let me switch to a calculator. So we’re going

to take, it is 102.8 and I’m going to multiply that times Avogadro’s number, which is 6.022,

oops I screwed up there. So let’s try that again. So it’s 102.8 times 6.022, I love this

key right here. What it does is allows me to write in what’s the exponent, so it’s times

10^23 equals that. And then I’m simply going to divide that by 18.02. And so the right

answer for that is 3.435 x 10^24. 3.435. So that is 3.435 x 10^24. Let’s do significant

digits. This has 4 significant digits. So that’s going to be my right answer. And so

that’s going to tell me how many molecules of water we have. So if you want to go back,

you could go back to that picture I had right at the beginning and you should be able to

figure out if this is 200.0 grams of H2O. Could you figure out how many molecules that

would be? If you were paying attention you should be able to. And I hope that’s helpful.

Very helpful thanks!

THE CALCULATOR SAID

3.435413984461709×10^24

NOT ×10^25

BUT THANKS. YOUR VIDEO IS HELPFUL.

THANK YOU I am in college (a sophomore) and you have taught me more that my teacher, lab instructor, tutors, and student instructors combined THANK YOU

I am honestly so grateful for people like you who are kind enough to share their knowledge to thousands of people. You honestly teach me more than my Chemistry ad Biology professors put together.

What is the answer for the 200mL of water?

isn't it supposed to 18.08 instead of 18.02 at 9:41?

Thank you so much 👍

thanks so much…it's really helpful..

THIS HELPED ME SO MUCH!!!! Also…. eyecandy. >.>

i did the practice problem is 6.681465×10^24 right?

this helped me so much my teacher sucks

For 200.0g(4 sig fig) of H20 you get 6.68368×10^24

but with sig figs final answers should be

6.684×10^24 atoms of H20

How come online "grams to moles" calculators are dividing number of grams by the amu of the molecule? They aren't multiplying number of grams by 6.022 x10^23 before dividing by the amu…

you are annoying

Mr.Anderson is the key to success 🙂

you rock

How would i do this problem? i think you have to use a different method to solve it, but im way confused about this:

How many particles of table salt is 32.5 grams of sodium chloride?

he is such a pusy

This helped me study for my exam tomorrow! Just once question? For the last problem, why is it 3.41 x 10^25…. i thought it would be 3.41 x 10^24?

thank you so much, you taught me more than my teacher has taught me in 3 weeks

Thank you so much! I will now be able to understand my chemistry class because of this video.

thanks for sharing ..you are a great help 🙂

Mr. Anderson, thanks so much for this fantastic video!!! The way you explain the relationship between molecules, moles and grams clearly, with the actual formulas necessary for each, and how to manipulate them from one direction to the other, is PRICELESS!!! Thanks for actually using the calc with us, as that's where many problems can happen. Love the glass board and terrific sound quality too!!! You're a chemistry ANGEL!!!

Bozeman, how is the exponent for the second problem "25", I thought the calculator said "24" on your screen?

my teacher loves this guy. we watch his videos all the time lol he does a great job at explaining

Really thank you =D

fml

Thankyou so much! This finally made sense to me, I learnt more in 10 minutes than I had all week with my actual teacher at school

Thank you so much!

You explained this so much better than my teacher. Thank you.

mole-tiply;-)

MR ANDERSON MATRIX XD

thnx for this video. actually I'm becoming grade and still don't understand, but in this video I learned a lot.

Thank uuuuuu!!!!!!

thank you sir , it is really informative ,and could you please explain about how to covert mole to mili mole and micro mole ,thanks

In order to go from moles to particles we need to multiply the mole number by avrogadros number not dividing it. thank u for this video now I understand it 😀

oh my, its awesome

can someone explain to me why dont usng 6.02×10^23 when converting the .200 moles of H2SO4 to grams ? 😛

can someone tell me why did the answer became 4.435×10^25 instead of the exponent being 24 before rounding off?

Thanks. My teacher isn't fit to teach.

Thank you

How come it is 3.435*10^25 and not 3.435*10^24

Thank you so much for making these videos it helps me out a TON with my schoolwork… dont think my teacher explains it well enough :/

y,v

Wow, thank you! My teacher is absolutely amazing, but I have been struggling with understanding this specific topic. Your videos are really helpful.

66.82×10^22 molecules

my prayers have been answered..u r awesome

why is it .200 moles.. how

thank you very much i just dont get it when my teacher explains it

my teacher is really good and respectable but didn't get this stuff quite right thanks Bozeman science

I HAVE A FINAL TOMORROW PRAY FOR ME!!!

Thanks this was really helpful I was struggling to understand this in class!!

thank you!! this cleared so many things up for me

Thank you!!! 🙂

super helpful

Am I the only one weirdly attracted to this man??

what about formula units to moles?

I got 6.683 * 10^24 for the answer to the last question, 200.0g H2O to molecules. Is that correct?

THANK YOU

Thanks. I slept through most of class so binge study is my #1

thank you so much! my professor sucks

wow thank you very much, this really helped me a lot

don't know how i got here but now i know i know this… great way of teaching man!

you look like if john green and hank green were one person

The answer is 66.83 × 10 raised to 23 molecules

You saved me in my senior year of high school in AP Bio, and you aboutta save me now in college with chem!!!

where did he get 18.02 grams of h20 from

My teacher sucks. Thankyou so much

Awesome explanation. Thnxxx

I love you

im just here because i have a big test tomorrow and i dont know what the hell im learning in class

You just saved my life in chem. It's such a hard subject for me, but you make it easy!

Teachers need not be blamed for this cause nowadays we have gone too addicted to technology that traditional teaching has lost its importance

And of course here its one on one ratio and in a class room it is not so.

It's so easy to understand. Thanks for making this video!

Where do I pay you?

yeh its quite good to explain children like this

The periodic table in the book I was had the mass of K threw off everything but I figured it out and the book was tossed.

I like your videos.

SIR

REF:–VIDEO ON MOLE CONVERSION

1. Liked yr video for its information content.

2.. All clear

THANKS

VATSA

damn was distracted by your face.

This is so helpful

Youre a god

thank you so much

hey just as constructive criticism, i strongly suggest that you don’t trail off your sentences. it is sometimes very difficult to hear the endings of your sentences bc you get quieter. great info tho!

Does anybody have a transcript of what happened in the video?

Is is only me that I got 10 to the power 24 not 25

Thank you sooooooooooooooooo much 👏🏼👏🏼👏🏼

Where did you get the periodic table??????????

OMG thank you so much this is amazing

Question: Why’d you put 3.435×10^25 instead of what you got in the calculator which was 3.435×10^24?

👍

Thank you TT

your voice is so relaxing

I got a 100 on the quiz yesterday because of you thx alot

How does the exponent in 10e23 raise to 10e25?

Thank you for the slow calm explanation. I was able to follow along.

I also learned how to use the EE button. Thanks! Very helpful video.

Wow.. Thanks.. I finally understood the concept..

Wow thanks!

why has this taught me more than my teacher has taught over the course of 2 terms 😂😂😂

my teacher barely speaks english thank you so much