Tuesday, November 24, 2009

Gases, Liquids, and Benchmark... Oh My!

We are cruising through the end of the year by finishing up odds and ends. We have finished covering gases, but we are still practicing math problems including Pv=nRt and PV/nT = PV/nT.

We have started liquids and have talked about the different kinds of solutions. We have briefly discussed molarity and will finish liquids tomorrow and after Thanksgiving. Molarity is the amount of moles in a solution and is a measure of concentration.

Today students will be taking their last benchmark to help them prepare mentally for the upcoming SOL (less than 2 weeks away).

Friday, November 20, 2009

Oops! I made a mistake!

Today students participated in a stoichiometry challenge entitled "Oops, I made a mistake!" where the students had to identify what I did wrong in the calculations. The mistakes were all different and students excelled at spotting my mistakes. I told them this meant they were not allowed to make any more mistakes on their own problems. :)

Tuesday, November 17, 2009

Beginning Gas Laws

Today we started learning about the behavior of gases and the factors that affect them. Gases are lightweight fast moving particles that generally have a lot of empty space between them. Because of this, they are easily compressible (pictured left). If not contained, gases can spread (or diffuse) to fill any size and shape container.

Gases are affected by pressure, volume, number of moles, and temperature. Changing any one of these variables, changes all the others.

Today we also learned the formula for the Law of Partial Pressure. Basically partial pressures add up to form total pressure. If the total pressure is given then you subtract the partial pressures.

Monday, November 16, 2009

Limiting Reagents and S'mores

Today we discussed limiting reagents - basically the ingredient that limits how much products you can make.

For a S'more, you need a graham cracks (to break in half), a marshmallow, and two squares of chocolate. If you have 10 marshmallows, then you can only make 10 sandwiches no matter how many graham crackers you have.

In a chemistry problem, you have to take what's given to you and convert to the other thing that is given to you (so two sets of conversions) and then determine if what you NEED is what you HAVE. It's really a thought process applied to stoichiometry and unfortunately a necessary evil.

Students worked on practice problems and munched on a S'more while they worked. 20 seconds in a microwave and your marshmallow is ready for the chocolate and the top graham cracker!

Friday, November 13, 2009

Stoichiometry Quiz and Door Decorating

The Louisa Lions football team is off to the playoffs at Liberty and to show some spirit, there was a door decorating contest for third period. I am a mean teacher in an SOL class, so assignments came first, and then door decorating.

Angie led our door decorating team with major contributions from Kelsea, Kaitlin, Patrisha, and Kelsey. Many other students in the class were very helpful and happy to cut, paste, and whatever else was asked of them. The girls worked through lunch and came in for zero block to make our door festive and spirited.

We did not win, but we are proud of our door because it is awesome.

Today students took their quiz on stoichiometry (converting using moles) and they did AWESOME! The most points off was 2 and all mistakes were very minor. The students should be proud of their accomplishment in a tricky chemistry math subject.

We will be learning limiting reactants on Monday and as a reward we will do this edibly.

Wednesday, November 11, 2009

Measuring Moles

Today students measure how many moles and molecules of water they could drink. They took some measurements and then did some mole calculations to figure everything out. The determined how many moles and molecules they could use when writing a message with a piece of chalk, and measured sugar by biting into a candy corn pumpkin. There are some interesting statements written on the board.

Everyone should take this one to heart, "If there is faith that can move a mountain, it's faith in your own power." I know that the students can do these calculations and most of my time these days is walking around confirming the student is right and pep-talking. They can do it... they just need to believe that they can.

Students then worked on practice problems for empirical formulas and percent composition. There will be a small quiz on Friday and students will continue to practice.

Friday, November 6, 2009

Percent Composition

Today students learned how to calculate percent composition based on formulas using molar mass and based on weights from word-based math problems. Once they got the hang of it, it was time for Science Friday festivities.

Students each had a piece of gum - one they brought in or one from me. They all brought in chewing gum (even though the board said bubble gum) and I brought in bubblegum, so there was some trading. Students observed the gum by weighing it, drawing it, and smelling it.

Next they chewed the gum for ten minutes. While they were waiting we watched How Its Made on bubblegum which is linked to the side if you want to see it (and then another episode about potato chips because we had time). We also had a little fun blowing bubbles. Ethan could blow the biggest bubbles.
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. We worked on making a data chart to make some comparisons and we will finish this on Friday.

Thursday, November 5, 2009

Guest Speaker and Mole Evaluation

Today students practiced moles and then took a short quiz about moles. They are all nervous about it, but I knew they could do it!

Then students listened to a guest speaker, Mr. Stuart Marshall, one of my former students who is now a funeral director. Mr. Marshall works in a chemistry-related field because bodies need to be embalmed or cremated. He also talked about how important it is to go to college and get an education. He started at community college and then moved onto a four year school. Students enjoyed the talk and asked a lot of questions.

Tomorrow we are going to have Science Friday and learn about Bubblegum and percent composition.

Wednesday, November 4, 2009

Mole Practice

Today students took a mole challenge to see how much they knew about moles... besides their favorite number. The high score was a 9.5/10 so I must have stumped them. They did do better than they thought they would... and most of them were a bit mad when they saw what the answers were to the ones they didn't know.

For moles there are basically three conversions to know.
1 mole
6.02 x 10^23

1 mole
(molar mass) grams (add weights from PT)

1 mole
22.4 Liters

Today we learned about Avogadro's theory about gases and then practiced converting using our new favorite number, 22.4. Avogadro, that handsome devil, did a lot of important stuff with moles and is also the guy who gave us our other favorite number 6.02.

Everyone seemed to have the hang of things so we got out the white boards and did some practice problems. Everyone tried the problems and erased any mistakes with ease. I know they know it even if they feel a little overwhelmed. Kristina and Elijah are pictured here concentrating and working out mole math problems.

Tomorrow the students will have a quiz and a guest speaker. The guest speaker is Mr. Marshall, one of my former students, who is know a funeral director using chemistry in real life.

Tuesday, November 3, 2009

Element for President Poll Results

Thanks to everyone who came out and voted for Element for President. With over 250 votes cast, your new Element President is……

Platinum (Amy)

The rest of the top 10 are…..

2nd Germanium (Kelsea)

3rd Antimony (Angie)

4th Potassium (Ryan)

5th Argon (Lisa)

6th tie - Radon (Steven) and Actinium (Amanda)

7th Xenon (Elijah)

8th Neon (Kristina)

9th Molybdenum (Megan)

10th Boron (Kelly)

Monday, November 2, 2009

Moles - the Beginning

Today, students started the day with a small review about coefficients, subscripts, and how to count atoms. We covered some of the material that was on the last benchmark and answered some questions and had a small discussion about test taking skills.

Then we started talking about moles. 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 practiced 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).

Homework tonight includes identifying parts of a reaction (unit 4 stuff) and finding molar masses unit 5 stuff).

Tomorrow is Election Day for Element for President! We will see which element campaigns the best!