Homework: Complete pages 18, 19, and 20 in Chem. Journal. Study Gram to Gram problems.

Announcements: Quiz in class today on simple Stoich problems. Mr. Paek did a class demo to show how oxygen reacts with gas. You should have a good understanding on Gram to Gram problems, if you are struggling go to TLC or talk with Mr. Paek.

Demo: Mr. Paek set up an experiment to show the equation CH4+2O2 --> CO2+2H2O. First he filled an empty paint can completely with gas from the bottom hole. There were two holes, one at lower side, and one at top of lid. Once the can was filled with gas, he lit the top hole and it gave off a flame. While the fire is lit, the amount of CH4 goes down, while the amount of Oxygen goes up. Overtime the flame got smaller and smaller because more oxygen filled the can by entering the lower hole. Once the amount of oxygen is double than the amount of CH4, the can gave off a explosion/sound. The point of this was to show the reaction of the equation above.

Grams to Grams Problems: Before staring the equation, make sure the initial given equation is balanced out correctly or else all your answers will be wrong. "MnO2+4HCl --> MnCl2+Cl2+2H2O" is correctly balanced. To start, when you are given a certain mass, you always put it at the beginning of your equation. Then just like the beginning of the unit, the next step is to change grams to moles by looking at the periodic table. The mass you find will be at the bottom of the line and "1 mole" of the certain atom will be at the top of the line. Next since your equation is at moles because "mole" is at the top of your line, now you can transfer over to another atom. Look at your balanced equation and see how much of a certain atom is equal to the other. Such as "how many pieces of bread do you need in order to make X amount of sandwiches?" If i use "x" and "y" to express the two different atoms, it should look like this. You should have your original grams of "x" times mole"x"/gram"x" times mole"y"/mole"x". Now that you have the mole "y", you want to convert "y" to grams. So you would put 1 mole of "y" under the line, and grams of "y" (found on periodic table) over the line. So now you should have grams"x" times 1 mole"x"/gram"x" times mole"y"/mole"x" times grams "y"/ 1 mole "y".

If this is still confusing visit Mr. Paek or the TLC for help because there will be a quiz soon.

Friday, January 28, 2011

Anouncements : Quiz Monday

Today in class : Today in class we learned stoichiometry. The basic idea is to use a balanced equation to figure out how much of one substance you would need to react with another. The simplest way to explain it is with the sandwich analogie. Lets say the basic recipe for a ham sandwich is 2 pieces of bread (B), 1 piece of cheese (C), and 3 pieces of ham (H). This equation would look like this: 2B+C+3H -> BCH. Using this equation we could find out how many sandwiches we could make with 6 pieces of ham or how many pieces of cheese we need if we have 14 pieces of bread. With the same equation we could also figure out how many pieces of bread we would need for 3 sandwiches. With smaller and more basic numbers like these we can solve the equation in our heads without much effort; however, when we have larger amounts like 33 pieces of ham these equations become more difficult. If we were trying to find out how many pieces of bread we need with those 33 pieces of ham we would have to multiply it by the ration of bread to ham given to us in the original equation. In this case it is 2 pieces of bread over 3 pieces of ham. In order to solve this we need to take the starting information of 33 pieces of ham and multiply it by the ratio 2 pieces of bread over 3 pieces of ham. It is important to remember that when you set up the problem that the same units always cancel out. That is why the 3 pieces of ham must be on the bottom in order to cancel out the 33 pieces of ham given to us in the starting piece of information. Now in chemistry, instead of sandwich ingredient we use molecules and elements. The ideas however are exactly the same. Take a balanced equation and use the information given to find the amount needed to cause a chemical reaction. We also learned how to find the exact mass of elements that we would need in order to cause a reaction. Back to the sandwich analogise, if a piece of bread weighs 2 grams, a piece of cheese weighs 1 gram, and a piece of ham also weighs 1 gram then we can find out the weight of a sandwich ingredient needed to make the sandwich. If we had 2 grams of cheese, in order to find the amount of ham needed we would multiply the starting amount by the amount of cheese needed to make 1 sandwich which is 1. So 2 grams of cheese equals 2 pieces of cheese. To convert that to ham we would multiply that by the ratio of ham to cheese 3pieces of ham over 1 piece of cheese. this gives us 6pieces of ham because the cheese cancels out. Finally to find the amount of ham in grams we simply multiply the 4 pieces of ham by the 1 gram each piece of ham weighs. When you put all this together you it ends up meaning that for 2 grams of cheese you need 6 grams of ham to make the sandwiches. Again, in chemistry we use the same concept but instead of grams of ham we use the molar masses to find the amount of a substance needed to cause a chemical reaction.

Homework : Pages 15 and 17

Announcements : No Announcements Today.

Homework: None. You should have pages 1-8 already completed.

Today In Class : We did not do much in class. To start of class we grabbed pages 9-35 and taped them in our journals. The pages went about two pages per paper. Before taking the first quiz out of 7, we reviewed a little bit. we talked about how to convert grams molecules atoms and moles. We then took the quiz.

There is a total of 7 quizzes. each worth 7 points. 49 points possible. if you get 7 perfect scores you will receive extra credit. also if you receive 5 perfect you will get extra credit but a little less. same goes for 6 perfect scores. You will need to get at least one perfect score to take the end test.

To end class we had a power point on stoich. for the power point we worked on page 10.

Wednesday, January 26, 2011

Announcements : -If you have any questions about moles find Mr. Paek ( he is free 5th and 6th period.) This is a really important unit and if you want to do good on the test you have to do good on the quizzes.

-Make sure to show all work and units in homework and quizzes, because it will get very confusing later on if you don't get in the habit of doing it right now.

- Buy a notebook if you haven't already.

- First quiz tomorrow/ 7 quizzes total this unit.

Homework: -pages 7-8.

Body: Today in class we went over some problems from pages 1-6.(Again: make sure that you go get help from the TLC or Mr. Paek if you don't get something.) Then we did a lab called: Moles Stations Lab. The lab had 9 stations, and in each one of them we calculated either the mass number, mole, or the number of atoms.

Set1: had to count the number of pairs of shoes in the room.

Set2:find the mass of Aluminum foil and find its mass number and how many moles it had.

Set3:find the mass of a carbon rod find mass number of it and how moles, then how many atoms.

Set 4:we had to find how many moles of Krypton in a graduated cylinder, and the mass of it.

Set 5:we had to find the mass of H2O, and the number of grams in one mole of H2O.

Set 6:find one mole of HCl, the number of moles in it, and the number of molecules.

Set 7:found the volume of an aluminum bar its density and the number of moles and atoms.

Set 8:find the mass if neon, and the number of atoms in it.

Set 9:find the mass of a balloon and the balloon's mole.

***examples from some problems in the lab:***

set 2: 1)The mass of Aluminum foil=3.74g

2) The mass from the periodic table = 27 g/mole

3)Number of moles Aluminum foil has=3.74 g Al foil*1mole/27g of Al foil=0.14 moles of Al.

set3: 1) Mass of carbon rod= 4.35 g

2)Mass from periodic table= 12 g/mole

3)Number of mole in this carbon rod= 4.35g carbon rod* 1mole/12 g carbon rod=.36moles

4)Number of atoms in rod=.36mol*6.02E23atoms of carbon/1mole=2.16E24 atoms of carbon

Tuesday, January 25, 2011

1/25/11

Announcements - The first of quiz in this unit will be his Thursday.

Today In Class - Today in class we started by picking up some new pages for our notebooks. We then went over the lab from yesterday that was supposed to be finished for today. Mr. Paek went over some of the problems and also made sure that everyone knew what they were doing. Once we finished going over the lab, Mr. Paek showed us how to find the molecular mass of a compound. For example, the compound NH4Cl . The name of this compound is ammonium chloride. To find molecular mass of a compound, you start by finding the atomic mass of each element. In ammonium chloride, N has 14. H is one, but since there are four H's, you would really have four H. There are also 35.5 Cl. After you have found all of this, you add it all together. Once you have added it all together, you will end up with 53.5 g/mol. After we were showed molecular mass, we went over conversions one more time.

Homework - The homework for today is every problem on both page one and page two. On page three, you only have to do problem one both a and b, and problem two both a and b. On page four, you have to do all of problem three, four, and five. On page five you have to do problem one, letters e, f, g, h. The last page you have problems to do for homework is page six. You have to do problem two, letters d, e, f, and g.

THE NEXT SCRIBER WILL BE.................... yassine

1/24/11

Announcements- There will be 6-7 quizzes this unit. If you get 5-6 perfect scores then you will get some extra points added to your quiz category. Also, in order to take the final test, you must have a perfect score on at least 1 quiz you take. If you fail to do so, Mr. Paek will not let you take it with the class until you do.

Today In Class- Today in class, after rejoining us to the class again and welcoming any new students, we were introduced to the mol. A mol is 6.02 x 10 to the 23rd power. We were also told that a pair=2 and a dozen=12. Then we did a lab that worked on using Unit Analysis for finding the number of atoms in a certain number of grams, the number of grams in a certain number of mols, and the number of mols in a certain number of grams. An example of a question for finding the number of grams would be: How many grams would 3.01 x 1023 atoms of Al (26.98 grams) be? 3.o1 x 1023 atoms x 26.98 g
6.02 x 1023 atoms
Then you would cancel out atoms and do the math.

Homework- Finish the lab. We're going over it in class if you have any questions.

THE NEXT SCRIBER WILL BE....... paul mcmahon

Hi everybody! :D I just realized that I can still log on to moodle which makes me quite happy so I thought I stop by and say hi :)