Moles are used to count atoms. There are 22,000,000,000,000,000,000 quintillion atoms in a grain of sand and even counting grains of sand is a pain. Because atoms are so tiny, we use the mole to estimate. There
are 6.02 x 10 ^23 molecules in one mole. That's a whole lot. This is
our new favorite number because it needs to be memorized. We will
practice converting from moles to molecules. Next
we discussed molar mass. Molar mass = 1 mole and it also equals atomic
mass from the periodic table. To find the molar mass of carbon dioxide
you find the mass of carbon and two oxygens and add them together.
Finding molar mass is not difficult unless the molecule has tricky
subscripts (which we have been practicing). The
third thing about moles is that "one mole of any gas will occupy 22.4
Liters." 22.4 is another favorite number. We can convert from moles to
liters and from liters to moles.
Just how big is a mole? There's a TedEd talk on that! Watch it here!
Percent composition is just like determining your grade - the amount you got divided by the the whole amount.
compounds, you find the mass of a particular element and divide it by
the mass of the whole compound. So if you wanted to know the percent
composition of oxygen in water, you would take the mass of oxygen and
divide it by the mass of water. We practiced some basics and the students measured the amount of sugar found in DubbleBubble bubble gum.
each had a piece of gum and observed the gum by weighing it, drawing
it, and smelling it. The students chewed the gum for ten minutes. While
they were waiting we watched How Its Made on bubblegum. After ten
minutes, students did more observations and re-weighed the gum. The gum
weighed less... why? Because the sugar dissolved and was lost. Using
this weight difference, students determined the percent composition of
sugar in the gum they chewed. They also can convert the grams to moles
and determine how many moles of sugar were in the gum.
Each week you will be asked to visit
a few online sources. You may be asked to read an article, watch a video, play
a game, take a quiz, listen to a podcast or all of the above. Sometimes you
will be given specific questions to answer. At other times you will be asked to
write a summary convincing others that they should check out what you found. These
assignments will take time so do not wait until the last minute. At all
websites, you will be asked to correctly write a citation.
Assignments will be given on Thursday and are due by the end of the
school day on the following Thursday. If you are absent, the assignment is due the day you return.
or dimensional analysis, are used to change one unit to another. This
is really useful when converting to metric units, but is essential to
chemistry in terms of mole conversions. Setting up conversions is a
skill so we started with learning the format. There are plenty of how to
videos out there on the internet for anyone needing a tutorial.
practiced conversions with some of the crazy things people do to get in
the Guinness Book of World Records - like longest ear hair, skinniest
waist, tallest man, etc. I think the one the kids thought was the
weirdest was the lady who can pop her eyes out 12mm. Check out more crazy records here!
Significant digits are used so that
our calculations are not more precise than our measurements. All digits
other than zero are significant.
the zeros that are the tricky ones. We went over the rules and then did
some practice situations. We will continue to practice this and all
calculations made for the rest of the year must be rounded to the
correct number of significant digits.
Notation is used for very large and very small numbers that usually
have a lot of zeros to make the numbers for manageable. Most students
are familiar with scientific notation and just need a bit of practice.
You can listen to an interview with Schmidt who developed the pain scale here (it is the first ten minutes) on a RadioLab podcast (I highly recommend their shows).
Velvet Ant found in Virginia is red and black and therefore relatively
easy to avoid. Velvet ants are actually female wingless wasps. More
information about it can be found here. What's the difference between poison and venom? There's a TedEd Talk on that! Watch it HERE. How does your brain respond to pain? There's a TedEd Talk on that! Watch it HERE! Want to know more about ant colonies? There's a TED talk on it. Watch it here. The original Compound Interest article on insect venom and the Schmidt pain index can be found here.
Chromatography is the separation of liquids based on particle or molecule size. Chromatography
is used to separate inks into the colors that make them up. Most inks
are mixtures of colors and the ink will separate into bands of colors
based on the size of the different ink molecules.The small particles
move faster and will move further up the paper strip (in the photo
black); the larger particles do not move as far (yellow). Some black
inks are actually made up of blue red, pink, and yellow. Pairs or
groups of students received a strip of filter paper and made a pencil
line about 3 cm from the end. They then traced over the pencil line with
a marker, dipped the edge of the paper into water and waited. Over time
the water will travel through the paper carrying the ink molecules with
it. Smaller molecules are easier to carry and travel further. Chromatography
can be used to separate any mixtures with different size particles and
actually gel electrophoresis used for DNA analysis works on a similar
portion is about the difference in toxicity of natural vs. manmade
chemicals. Most people wrongly assume that if a chemical is natural that
is good and that if a chemical is manmade then it is bad. Both can be
good and both can be bad!
Compound Interest's original post about Lethal Doses of Common Chemicals can be found here. Compound Interest's original post about Natural vs. ManMade Chemicals can be found here.
of us have seen these diamonds on trucks as we pass them on the
highway. These diamonds are useful for safety and response teams to
identify what is in the truck so the correct precautionary and clean up
measures can be made.
NFPA 704 fire diamond (or hazmat diamond) is described in NFPA Standard
704, maintained by the National Fire Protection Association. The system
identifies four key hazards (health (blue), flammability (red),
instability (yellow), and special (white)) and their degree of severity.
Hazard severity is rated numerically, ranging from 0 (minimal) to 4
hazard diamond is useful because it allows emergency personnel to
quickly and easily identify the risks posed by hazardous materials and
is useful to determine what, if any, special equipment should be used,
procedures followed, or precautions taken during an emergency response. (Summarized & more information here.) Want to make your own customizable hazard diamond? Click here. Why does this feature exist? So people can make easily identifiable hazard diamonds for any chemical they have on hand.
need to be familiar with certain lab equipment and its purpose, even if
we won't use all of it in labs for high school chemistry. Students
identified equipment using examples of the real thing (we made this into
a contest) and also by identifying black and white drawings.
Students will sort equipment based on what its main purpose is. Some equipment is used for liquids, some for solids, and some for heating. Some is used for all of those things. The
three pieces of equipment most likely to come up, and the most
confusing when in black and white photos are the watch glass,
evaporating dish, and the crucible (which has a lid). All three of these
can be used for heating substances to remove water among other things.
In real life they look different - but in drawings they look similar.
How to tell them apart? The watch glass resembles a contact lens; the
evaporating dish has a pour spout; and the crucible is more cup shaped
and often is pictured with a lid. Here is an online quiz on lab equipment with photos! Try it!
Greetings students, parents, and guardians. Welcome to a
new school year with Ms Jancaitis! This blog has been set up to connect
students, parents, and guardians with the chemistry class. Each student
will receive a course syllabus. The course syllabus outlines what the
course will be like, what topics will be covered, and course
expectations. It also contains contact information. There will be a quiz
on this syllabus on Friday. Our first unit
will cover lab safety and equipment. Each note packet comes with the
safety rules and contract. The safety rules and contract need to be read
and signed by both the student and parent guardian. The safety rules
are rules designed to keep the classroom safe and orderly to maximize
learning and prevent accidents and injuries. These rules need to be
studied because there will be a safety test on Monday and
infractions of these rules can lead to disciplinary action as well as
low assignment grades. A contract holds students accountable for the
items that are broken if the student is acting a manner that is unsafe
for themselves or those around them. Please have
these papers signed and returned by Monday. Students not
returning signed safety rules and safety contracts will not be able to
participate in labs and activities until the contracts are signed and
If you were absent for the Physical versus Chemical lab, you can make up the majority of it by following the link below and watching YouTube videos of the experiments. You can also just check them out because they are cool.
Open a link in a new tab. In the blue box, look for "Play Games" and "Scatter." You will then need to drag the names to the correct formula. If it disappears, you matched it correctly. Play each set a couple of times until you get really good. You can also use these as flashcards and make up and take tests.
Click on the rice above to test your knowledge of the Periodic Table while earning rice for the United Nations World Food Program. You can also test your knowledge of vocabulary as an excellent SAT prep.