Step by Step Density Practice Problems to Help You Pass Chemistry

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…

28 thoughts on “Step by Step Density Practice Problems to Help You Pass Chemistry

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

  2. 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?

  3. 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??

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

  5. 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.


    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

  7. 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?

Leave a Reply

Your email address will not be published. Required fields are marked *