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!
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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.
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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...