Finally I’ve been waiting for you some

might say it’s coincidence but I think it’s density. In this video you are going

to learn how to calculate density and how to use it as a conversion factor.

Alright let’s do this! [Music Playing] Hello Hello, Melissa Maribel here and I help students like

you understand what you just learned in class so you stress less and you

graduate faster so if you’re new here consider subscribing. So we’re talking

about density. Density is mass within a certain

amount of volume. Our formula is mass divided by volume. The proper units that

you’ll notice for density are grams per centimeter cubed or grams per milliliter.

Let’s jump into our first example that uses density as a conversion factor. What

is the mass of 25.0 milliliters of octane with a density of zero point

seven zero two grams per cubic centimeter. As always start with

identifying your given, conversion factor or factors and what you are finding. The

given is twenty five point zero milliliters, your conversion factors one

milliliter is equal to one cubic centimeter then we’ll use this to get to

grams using the density as our second

conversion factor, so one cubic centimeter is equal to zero point seven

zero two grams. Lastly we are finding mass, mass if it’s

not otherwise stated is measured in grams

the plan is going from our given unit milliliters then using our first

conversion factor to go to cubic centimeters lastly we’ll use our density

as our second conversion factor to get to grams.

Our proper setup placing are given in the beginning as always 25.0 milliliters

align the milliliters across from each other so they can cancel out, next we’ll

use our first conversion factor and we’ll get to cubic centimeters aligned

those units once again so they can cancel out and finally placing our

density at the very very end so we’ll get our unit that we’re looking for

which is grams. Multiply straight across and really divide by one you get

seventeen point five five grams however we have three sig figs since our given

was one to three significant figures we’ll round this five on up and our

final answer is seventeen point six grams. Let’s incorporate density and

dimensional analysis. The density of titanium is four point five one grams

per cubic centimeter. What is the volume in cubic inches of 3.5 pounds of

titanium? Start with identifying your given and your conversion factors since

there are multiple in this question and what you are finding. The given is three

point five pounds and our conversion factors we actually have four in this

case. To get from pounds to eventually grams will go from pounds to kilograms

next we’ll use kilograms to get two grams using the metric system our third

conversion factor is the density which was provided which is four point five

one grams for every one cubic centimeter next we want to get to inches so we’ll

use our last conversion factor 2.54 centimeters to get to one inch and we

are solving for inches cubed. As we saw before we have four conversion factors

our plan is starting with our given unit which is in pounds using our first

conversion factor to get to kilograms then we’ll use our second conversion

factor to get to grams our third conversion factor which was a

density to get to cubic centimeters and lastly we’ll use our fourth conversion

factor to get to inches and we’ll see that we will have to cube at the very

end. Our given is what we start with 3.5 pounds aligning those pounds across from

each other so they can cancel and let’s do this together so our

pounds cancel out on top is our kilograms once again we’ll align into kilograms

across from each other so those kilograms also cancel out we’re

now to our third conversion factor and we’ll align the grams across from one

another so they can cancel, you see the pattern but we see that this is not

cubed so we cannot cancel these two out this entire conversion factor then has

to be cubed once we do this we will cube that 2.54 and we’ll get centimeters

cubed as well and one cubed is actually just one but our inches cubed will now

be there as well let’s cancel all the different units are pounds cancel

kilograms, grams and cubic centimeters finally cancel leaving us with the unit

that we were finding all along cubic inches multiply straight across and

divide by two point two four point five one and sixteen point three eight seven

all multiplied. You get two point five three cubic inches however our given was

only two sig figs so we’ll go ahead and round up our final answer is 22 cubic

inches. Let’s calculate density. Calculate the density in grams per milliliter of

aluminum with a volume of zero point six cubic centimeter and a mass of four

point six milligrams you’re gonna have two different givens

we have the four point six milligrams and zero point six cubic centimeters

since we are solving for density we have a formula for that our mass divided by

our volume but specifically we want the unit to be grams per milliliter.

Step one is taking our milligrams and converting them to grams our given was

four point six milligrams always aligning the milligrams across from one

another so they can then cancel milligrams cancel we now are left with

four point six times ten negative third grams. Step two we’ll take

our cubic centimeters and convert them to milliliters

that 0.6 cubic centimeters then gets aligned with our conversion factor of

one cubic centimeter to one milliliter cubic centimeters cancel multiply

straight across we’ll get zero point six milliliters and our last step is just to

divide our grams divided by our milliliters so step 1 divided by step

two we’ll end up getting grams per milliliter. Okay here’s a pen, now try

these practice problems. [Music Playing] How’d you do? Do you feel like you need

some more practice if so check the description box below there’s a link

with practice problems and step-by-step answers and remember to like this video

if you learned something and subscribe if you want to see more videos just like

this one and remember I am here to help you pass the chemistry so leave a

comment below letting me know what you need help with and I’ll see you next

time. Okay Alright, let’s do this! Ow Alright let’s do this. What no, where are you? Did you want me to do it all over again. Random Hand: Yep Melissa Maribel: Ohhh…

Your videos help me so much!

While I did the math I got 21.43 instead of 21.53… what am I doing wrong??

Thank God without your videos i don't know if i could pass my chemistry class …. phewwwww ? thank you !!! ❤️

Thank you so much! I learned more from you in 1 video than from my teacher in 1 week 🙂

thank you some much. you helped me understand better and even gave me information i missed during the lecture by the teacher.

This is great!!

This is so amazing. Thanks for your help!

for the density problem where did the 10^-3 come from?

OMG so glad I just ran across this, so helpful.

How do you know to use cm3 to get to grams?

Can you do a video on solubility curves? 🙂

Thank you I was so lost at school now I know what I'm doing

I have a question. How do we find the conversion factors? Like from pounds to kilograms to grams, how do we know which units to use?

I love ur vids but my problem is how do you know you you need to go to mL to cm to g?? I don’t understand how that happens why not ml to nm?? Like how do you know its to cm??

How come another tutorial teacher says you should leave the answer in 3 significant numbers? Please respond

i dont understand

Why can’t you be my professor!! This was sooooo helpful!

Aww, I was hoping this would be helpful but the way she set it up just confused me even more. ?

just got done watching and this was quite helpful however i still need the help. the "in deth how to guide on density" is not working. when i click on it it says it does not exist.

THANK YOU QUEEN UGH I WAS SO STUCK BUT U JUST HELPED ME??

Your links to the practice density problems are broken. Can you reupload them?

I love you I love how you have a cute YouTuber setup but it’s chemistry ! So fab.

Am I supposed to already know the conversion factors? 🙁

i still don’t understand ?

I LOVE YOU THANK YOU QUEEN ?

CAN YOU ANSWER THIS QUESTION???

what is the volume in mL for gold if the price is 17 kg. The density for gold is 19.3 g/mL

I am stumped on this

God Bless you Melissa! This is really REALLY helpful!

Hi, I did the last practice problem exactly how you showed in the video and I got 59 inches cubed and I was wondering if that's what you meant by 95 (just a typo) or if it was something I did wrong?