evaporation of liquids

evaporation of liquids

Articles, Blog , , 0 Comments


argh mateys today we’ll be talking about
evaporation. Im eating a buttescotch rum lollypop. Where is the rum when you need it right? all right all kidding aside let’s talk about
evaporation. On Tuesday we will have discussed evaporation, intermolecular
forces. intermolecular means attractions between molecules not
between particles within the molecule. Not a bond but an interaction between
the molecules. Our beginning question is how do intermolecular forces affect
evaporation of a liquid, and also how does the mass of a molecule affect evaporation. So we’ll be
testing two different things. You’ll have a set up with
test tubes or have a test tube rack out and test tubes and you will have probes
and temperature probes up to the lab quest. This is what we using for the
lab. First thing you need to do in the prelab you need to
draw the structural formulas for each of these substances, calculate the molar
mass and identify if t hey have hydrogen bonding. First make a DataTable in your lab
notebook and titled first column substance, the second column formula , the
third column structural formula , the fourth column molecular weight, and the
fifth column does it have a hydrogen bomb yes or no. You need to draw let’s try structural formulas the first one we’ve got two
carbons. two carbons are going to go in the middle we know each carbon can have four bonds 4 electrons in each bond we can tell CH3 that the first carbon is bonded to
three hydrogen and the second carbon, which is then bonded to two hydrogen and the last carbon
the last bond on carbon is 2 hydrogen and an oxygen bonded to
an hydrogen. this is ethyl alcohol that the first for alcohol. You guys can calculate your and molecular weight the second one we’ve
got a chain and I left one out and I already sent to print. great. it should be
CH 3 CH 2 CH2 0-H because we have three carbons first carbon is bonded to 3
hydrogens to second is bonded to to two hydrogens, the third is bonded to two
hydrogens and last is bonded to oxygen and hydrogen. Propyl means three butyl means 4. 1234 carbon so
we’ve got that at least drawn written correctly there ch3 ch2 ch2 ch2 O-H. methanol is very simple to draw we have
carbon bonded to three hydrogen bonds and I1 O- H. Pentane we’re gonna have a
chain of five only this time and once again I wrote them wrong and I didn’t
proofread it. we’re not going to have a O_H the end so it 12345 carbons
carbon is bonded to 123 hydrogen bonds to hydrogen CH2 CH2 toCH2
can finally CH3. you guys can calculate the molecular mass.
is hexane, again bad mistakes on my part i guess im gonna rewrite all those a hexane is CH 3 ch2 we’ve got six carbons this time then
ch2 ch2 ch2 ch3 again. for our procedure
step one and wear goggles and I don’t have a set of goggles on the desk so
just pretend like I put them on. Set up meter scale so you’re going to get your
lab quest out, meter scale is when you have the picture open it has the red
area on it tap llength so you’ve got your instructions
say to chooese length but it’s not length its duration and it is the third box down.
first one is mode the second one i think is samples per second and then
duration you’re gonna click duration and you’re going to change your time to 60
seconds and then hit OK 3. with a little bit of filter paper and
this happens to be one left over from last year so what we did we had the
filter paper cutout of a coffee filter and they’re probably all the same size
and I’ve got little orange rubber bands and you’ll just wrap those rubber bands
around the end of the piece of paper on ther. so you’ll have paper that you’ll
wrap around the and the group must run it so here’s our probe could take paper
and wrap it around and then you use a rubber band
securily so in the end it’s gonna look like this. you have two of them make sure the containers are so sorry
getting ahead of myself step 3 Put the probe
in the test tube container. see you you’re going to have a test tube rack
and you’re going to put one probe into the one that says ethanol in one probe
into the one that says propanol. after the probes have been in there for
30 seconds hit start. that’s a little greener triangle. wait for
5 seconds and then pull both probes out and you’re gonna tape them to the edge
of the table. I’m gonna tape them
down so one person start the timer, one person is gonna be ready with the
tap,e the other person’s gonna have the probes or maybe two people have
probes idown in the whole time it’s collecting data and you want to
have them so they’re hanging off the edge said that they can start to
evaporate Here’s the probes there’s tape
Here’s the edge of the table we’re taking one probe and another
one right next to it with her little paper on the end and we’re going to get
tape and tape them down step 6 data collection was stopped after
one minute and I’ll stop so you don’t have to hit the red
button. Examine the graph of the temperature versus time so you’ve got a
graph based on your data to determine the maximum and minimum temperatures so
you’re gonna have had a temperature in your gonna find a max and a minimum
and record and you’re gonna need to record that into a DataTable that looks
like this.l alright so hit pause and go ahead and copy that down to really put
the data into that data table. step 7 you subtract the minimum from the
masks and record it back in the DataTable you just write and enforce
step 8 you will repeat steps 3 through 7 with butanol and pentane and then 7-9 you repeat again for methanol and hexane and there
you go that’s what you need to get down so you need to have two
DataTables one with the structural formulas and the molecular mass and
whether there’s hydrogen bonds or not and the second line with your
temperature your max temperature your minimum temperature and your temperature
difference thank you for playing with me today

Leave a Reply

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