11.06.12
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It’s Molection Day!

Okay seriously though this photo reminds us of two major events occurring today:

  1. It’s Election Day! It does not matter who you vote for, only that you vote! Mrs. Bassinger here and the rest of the social studies department will be putting on a mock-election. What a great way to exercise some good old American Patriotism. ‘Merica!
  2. Our Moles are due this week and some of them have already been turned in. The “Voting Mole” pictured here was a very clever idea. Check the “Photos” page for more of our creative creations!
11.05.12
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Atoms – Moles- Molecules

This week we take the next step in the evolution of mole conversions. So far we have worked on one side of our graphic organizer or the other.

  • Mass of Atoms – Moles of Atoms – Atoms
  • Mass of Molecules – Moles of Molecules – Molecules

This week we connect the dots. This week you’ll be given a mass of molecules and work across the graphic organizer to get to mass of each atom that makes the molecule. ( For example: Mass P2O5 Molecules = Mass of P atoms + Mass of O atoms )

You’ll need to follow dome simple steps, which you have learned how to do in past lessons, in order to come up with your final figures.

  1. Calculate Molar Mass of the molecule (Multiply atomic masses by subscripts; add)
  2. Calculate the moles of the molecule (Given / molar mass)
  3. Calculate the moles of one of the atoms that make up the molecule (moles of molecules x subscript of atom)
  4. Calculate the mass of those atoms (moles of atom x atomic mass)
  5. Calculate the moles of the other atoms that make up the molecule (moles of molecules x subscript of atom)
  6. Calculate the mass of those atoms (moles of atom x atomic mass)
  7. Check your results with the law of conservation of mass (Mass of Molecules = Mass of atoms + Mass of atoms)

 

10.30.12
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Moles to Molecules

We’ll be continuing our use of the Mole this week by using it to do calculations with entire molecules, not just atoms. So, we’ll be adding a whole new side to the chart that we started last week. See below.

If you’re struggling to remember how to calculate Molar Masses, search for the post on “molar mass” on this site. We’ll have a quiz over moles on Thursday and knowing how to use this chart to find the units you are looking for will be very helpful. There is also a homework assignment tonight (Grams to Moles to Molecules) which can be found on the “Docs” page. If you’re struggling with the calculations, watch the Voicethread.

10.26.12
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1 mole = 6.022 x 10-23 atoms = Atomic Mass

Lets say you have 2.5 moles of Au (Gold) and you’re really curious as to how many atoms of gold are in that sample. What should we do? Well just remember what Chemistry Cat says about MOLE PROBLEMS:

For any element or compound, 1 mole is equal to Avogadro’s Number of particles of that element or compound.

1 mole = 6.022 x 10²³

So, lets start plugging into a factor label equation the same way we did for Moles to Grams equations.

2.5 mole Au atoms   ->   __________  Au atoms

Since 1 mole is equal to Avogadro’s number, we can put that into our formula as…

6.022 x 10²³ Au atoms
1 mole Au atoms

So lets put this value into our formula and see if we can make this work…

2.5 mole Au atoms   x   6.022 x 10²³ Au atoms
1                                      1 mole Au atoms

We can cross out the “mole Au atoms” units so the only unit remaining is “Au atoms“. So…

2.5 x 6.022 x 10²³ Au atoms       =       1.506 x 1024 Au atoms

___________Easy! When you go from grams to moles you MULTIPLY BY THE ATOMS!_______________
But, what if I want to go from atoms to moles??? EASY!!! DIVIDE BY AVOGADRO’S NUMBER!
How many moles of Zn is 2.75 x 1024 atoms of Zn?

2.75 x 1024 Zn atoms   x   1 mole Zn atoms            =  4.57 mole Zn atoms
1                                      6.022 x 10²³ Zn atoms

Since, 1 mole of any element = Avogadro’s number of atoms (or molecules), you can flip the equation to work for you! Since we have moles on the top left of the formula, we want moles on the bottom right so they can cancel out!

Your homework for tonight is to finish the second 10 problems (the back side) of the  Moles Conversions Worksheet (found on semester 1 Docs). You can also watch the Voicethread on mole conversions using the App or the semester 1 Notes Page.

10.24.12
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Moles to Grams… Grams to Moles

After the excitement of MOLE DAY, it’s time to actually start using those friendly moles to our benefit. Today, we’ll be finishing the third part of our Mole lab with Cu/Fe. As a part of that lab, we’ll need to calculate how many moles of Cu/Fe were produced using the amount of grams of each.

To calculate grams to moles we use the FACTOR LABEL method. Let me show you what I mean…

Lets say you weighed your sample and have 105.5 g Cu atoms (Its important to label your values this way for future use; we’ll always add the element and “atoms” after the unit) and we want to know how many moles that is. well what do we know…

105.5 g Cu atoms   ->   ??? mol g Cu atoms

Well… lets think about this. Do we know how many grams are in 1 mol Cu atoms so we have something to compare this to??? Let’s look at our handy-dandy periodic table; find Cu; the atomic mass listed there is equal to the weight of 1 mol Cu atoms!

1 mol Cu atoms
63.5 g Cu atoms

So lets put this value into our formula and see if we can make this work…

105.5 g Cu atoms   x  1 mol Cu atoms
1                                  63.5 g Cu atoms

We can cross out the “g Cu Atoms” units so the only unit remaining is “mol Cu atoms“. So…

105.5 x 1 mol Cu atoms       = 1.66 mol Cu atoms
63.5

___________Easy! When you go from grams to moles you DIVIDE BY THE ATOMIC MASS!_______________
But, what if I want to go from moles to grams??? EASY!!! MULTIPLY BY THE ATOMIC MASS!
What is the weight of 2.5 moles of Carbon atoms?

2.5 mol C atoms x 12.0 g C atoms  =  30.o g C atoms
1                           1 mol C atoms

Since, 1 mole of any element = atomic weight of that element, you can flip the equation to work for you! Since we have moles on the top left of the formula, we want moles on the bottom right so they can cancel out!

Your homework for tonight is to finish the first 10 problems (the front side) of the Grams to Moles Conversions Worksheet (found on semester 1 Docs).

10.19.12
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Test Day!

Nice try.

In association with the shortened periods for Fall fest. I have adjusted the test so that it only has 45 questions worth 90 pts. total.

There will be calculations, but the test is entirely scantron (T/F, MC, & Matching).

Good Luck!

10.18.12
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The Password is… “Positron”

Our review game for today is the old school game show “Password”.  The same Powerpoint used in class will be available after school via the semester 1 Documents page for you to review with. My suggestion would be:

  • If you’re by yourself, use the pages as flashcards and say what you know about each term out loud
  • If you’re with other chem students, give each other clues in the same way the game is played.

It’s important to point out that although the game is fun and a good tool to review vocab, most of your test will be based on performing problems and calculations. Make sure you can complete the following:

  1. When given an isotopic symbol, identify the number of Protons, Neutrons, & Electrons.
  2. Correctly change the number of electrons in Cations and Anions.
  3. Identify a common isotope using the atomic mass of an element, then rounding that number.
  4. Calculate atomic mass using actual atomic masses & percent abundance of isotopes
  5. Complete nuclear reactions (Alpha & Beta)
  6. Complete a nuclear decay scheme
  7. Identify particles by their symbol
  8. Complete a half-life chart.

Use your study guide and the answers from the documents page. Watch the voice threads and go over notes to help you review.
Please contact me via email if you have questions tonight. Feel free to come see me before school for extra help as well.