Post-test day for Unit 6

SYNOPSIS FOR FRIDAY, DECEMBER 20, 2013

TEST:
The class started off by taking questions about the test. Ms. Friedmann also stated she will grade the lab test over break. If you have not taken the test, please contact Ms. Friedmann.

LECTURES:
The next topic was the GBS Stoich-A-Thon that will take place after break. This is a day where our class, joined with others, will complete extremely difficult Stoich problems in order to prepare for the chemistry final the following week. This has been a hit in the past as well as a fund being raised simultaneously.

The "Spirit Fund" is established to allow students to participate in the school who are chosen to receive aid anonymously through socio-economic need. These students are among us are sometimes unable to participate in all the school activities due to life's other needs. The sincere expressions for participating in the life of the school makes the fund continue today. Life is more about Stoichiometry and the goal of this Stoich-A-Thon; it is helping other students in the process.

Ms. Friedmann then gave us an introduction to the 4-day unit that we will be completing before finals on the topic of nuclear chemistry. Ms. Friedmann made a point that this is more of a physics unit rather the chemistry.

She then began to show us "The Manhattan Project" video by National Geographic. This is a 50 minute video on that we were not able to finish in class due to time constraints. However, Mrs. Friedmann has posted the link to this 5-part documentary on YouTube. This will be posted on the Moodle page, so students have the opportunity to finish this video over the break.

This is the atomic bomb.

HOMEWORK:
The homework over break is to raise money for the "Spirit Fund" over winter break.
It would also be great if students could finish watching this video over the break.
It is optional to start studying for the dreaded finals with the review packet that Mrs. Friedmann will post on the Moodle page for whomever wants to begin reviewing.


The next blogger for the Monday after break is...Kevin M.

Test Review!

Overview: 

Today we basically reviewed for the test that is happening tomorrow. We received our quizzes back and Mrs. Friedmann reviewed the concept of ions losing and gaining electrons.

Quizes...

- we got back the quizes we took a long time ago

- the test review packet was NOT graded. Its purpose was to inform you about what you needed to review for the teast

Losing and gaining...

- We also discussed how ions gain and loose electrons to achieve a perfect octet

             - a octet is when the highest energy levels of an ion have 8 electrons as a total

                 -EX: Iodine has a -1 charge because it gains an electron to have a perfect octet

                           - it could also be though as the ions want to achieve the same number of electrons as the noble gas that is closest to them have. For example, the most close noble gas to iodine is Xenon with 54 electrons, so Iodine with 53 electrons gains 1 electron to have 54 electrons, since it is easier to gain 1 than lose 18 to match Krypton with 36 electrons.

REMINDERS

- answer key to review packet is posted. Study hard!

- No review session tomorrow!

- TEST TOMORROW

REMEMBER, REMEMBER!

next blogger is... Jordan C.

Periodic Trends

12/17/13

Hey Guys!

At the beginning of class, Ms. Friedmann checked our Unit 6 Review packets. She will check the other homework tomorrow (which is the 4 worksheets on the periodic trends.) Tomorrow morning will be the study session. It will be in the same place at the same time (7AM)

We took a quiz today. All you have to do is put the answers from your packet on a scantron. Please make it up as soon as possible if you were absent. 

We also finished taking notes today which is already posted under the Unit 6 Notes folder.

If you are confused, try reading the textbook. For example, on pages 155-156.

Overall, good luck studying for the test which will be on Thursday!

Study tools:

Next Scribe is...Ambreen A.

Trends in the Periodic Table

12/13/13
We had a sub today for our quiz. We were given the whole period for the quiz, but if you finished early you were to start working on the Coulombic Attraction Packet, which was due Monday


12/16/13

To start class:
Mrs. Friedman reminded us that because we are being given less help this chapter, there will not be a video posted before the test. The test is on Thursday and the review will be Wednesday in the morning instead of Thursday.

After that, we went over our homework. Note: for #7 of page 4, you couldn't find the mass number because you weren't given the number of neutrons. A key thing to remember about the Coulombic Attraction Packet is that as the distance between the electron(s) and the proton(s) increases, the force of attraction decreases. In order to increase the force of attraction while the distance stays the same, the number of protons must increase.

Trends in the Periodic Table

1) Atomic Radius (aka atomic size)
2) Ionization energy
3) Electronegativity

Today we only got through the trend of atomic size. The notes are posted on moodle, but here is the basis of it:
a) As you move down the columns of the periodic table, the size of atoms increase.
Ex. A hydrogen atom is smaller than a lithium atom, which is smaller than a sodium atom.


b) As you move from left to right on the periodic table, the size of atoms decrease. This is because the added protons will increase the force of attraction and make the atom more compact. The added electrons remain on the same energy level as the previous farthest electrons and will space out from the other electrons, thereby adding little force to compete with the nucleus.
Ex. A sodium atom is smaller than a silicon atom, which is smaller than a argon atom.



Homework:
The review packet is due tomorrow.
Finish the 4 sheets that were handed out today (on moodle)
Check your Coulombic Attraction packet with the key on moodle.

The next scribe is..
Suvd D

Valence Electrons and Abbreviated Configurations

Notes

For the majority of class, we took notes.  They can be found on Moodle under the Notes section or right here : http://gbs-moodle.glenbrook225.org/moodle/file.php/12015/1314_Unit_6/Unit_6_Notes/12._12.13_Class_Notes.pdf

Quiz

We have a quiz tomorrow in class.  It covers everything we have learned in class so far (Atomic Scientists, models of atoms, electron configurations, orbital diagrams, quantum numbers, and the electromagnetic spectrum).

Homework

Today's homework is :

1) Complete the fourth page of the "Electron Configurations and Orbital Diagrams" worksheet (posted in the Unit 6 Handouts folder).  Today's class notes have been posted, too.

2) Complete the "Shells, Subshells, and Orbitals" worksheet posted in the Unit 6 Handouts folder.  I will collect this in class tomorrow.

3) Quiz tomorrow on everything we've learned in this unit so far.  This will NOT be a partner quiz.  People who are at Snowball, plan to make this quiz up on Monday.

The next scribe will be Colin S.

Electron Configurations and Quantum Numbers

Today, because of the shortened periods, we only reviewed the homework from last night.

Homework

Mrs. Friedmann told the class that our homework for tomorrow was to complete the third worksheet of "Electron Configurations and Orbital Diagrams".  If you do not have the Worksheet, it is posted in the Unit 6 Handouts folder on Moodle.  The other worksheet we have to complete for tomorrow is the Quantum Numbers WS #2, which we received in class today.

Important Upcoming Dates

Mrs. Friedmann told us today that we will have a quiz this Friday.

Since we didn't do much today, I will still be the scribe for tomorrow.

Electron Location Mapping: Orbital Diagrams and Electron Configurations

Tuesday, December 10th

BAND-AIDS

As we walked into class today, we each got handed a band-aid.  After practicing opening band-aid wrappers with Mrs. Friedmann until we were ready, we were allowed to actually open them in the dark.  If you watch carefully, you can see the inside of the wrapper spark blue when opened quickly.  Band-aid wrappers are triboluminescent because of the breaking of chemical bonds as they are ripped apart.

NOTES

We then took notes on how we can map the location of electrons in the atom.  As per usual, these can be found on Moodle.

HOMEWORK

The first two pages of the sheet titled “Electron Configurations and Orbital Diagrams” are due tomorrow.  Last night’s homework will also be checked in tomorrow as it was not checked in today.

Optional: Read "Bill Bryson - The Mighty Atom" (posted in the Unit 6 Notes folder) for background information.

The due date for the review packet has been moved to next TUESDAY, December 17th, and our unit test will be on Thursday the 19th.

There might also be a quiz on everything we learned so far on FRIDAY of this week...

The next scribe is Peter D.

The Electromagnetic Spectrum, Bohr Model, and Orbitals

12/9/13
Scribe Post: Juliette Ovadia

Agenda

Today, Mrs. Friedmann checked in our homework from over the weekend, the Light and Energy worksheet.  We did a short activity on the line spectrum. Then, we quickly reviewed the notes we took in class on Friday and took more notes on the Electromagnetic Spectrum, Bohr's Model and beyond and Orbitals. We did not finish the notes, stopping at n=2 in the table, however these are posted on moodle.

"Magic" Glasses and Hydrogen

In our notes, we learned about the electromagnetic spectrum, not just visible light.

When you shine white light from a light bulb through a prism, you can see all the types of visible light, ROY G BIV, and the long wavelengths (ROY) bend less while the short wavelengths (BIV) bend more.

Glasses were handed out that allowed us to see the visible light (colors) from the lighting in the room. Then, using a gas discharge tube containing hydrogen, an electric charge was sent through it like a neon sign. The light from hydrogen was shined through the prism, and with our glasses we could see the hydrogen's "line spectrum", only red, blue, indigo, and violet-- just four colors could be seen.

This is called the LINE SPECTRUM, the "element's fingerprint". Every element has a different line spectrum, as shown by Bohr's complicated mathematical equations.


The "They Might Be Giants" video we watched about ROY G BIV is below.



Notes

The image in the notes below shows that an electron goes from ground state to a high energy state, falls back to the ground state, and to get rid of the energy releases a specific wavelength (line spectrum), not the entire rainbow. This is because the electron must jump a SPECIFIC distance, therefore when it falls it releases a specific wave of energy.

On the Bohr Model and Beyond Notes, it's important to remember that wavelengths of light released depend on how many level the electron jumps and falls.

Some other things to understand is that Newtonian physics works beautifully for large, everyday things. But get really small or really big and Newtonian physics breaks down, and you need a new kind of physics, which is Quantum Mechanics. 

Orbital: wave function, area where you will probably find an electron

Heisenberg "uncertainty principle": you cannot know an electron's position and momentum at the same time. One must assume for the electron to jump from energy level to energy level it must simultaneously disappear from its position and reappear in another position, which is only possible on the quantum level, and scientists still do not totally understand how or why this happens.

Homework:

2 Webassigns (Due tonight at 11:59 PM)
Quantum Numbers Sheets (2)
Make sure all notes are copied into notebook!

 ROY G BIV Video

The next scribe is Valerie K.

Rutherford Simulation Lab

Rutherford Simulation Lab

Mrs. Friedmann wasn't in class today so the sub took us up to the math lab where we worked on the computers to complete the Rutherford Simulation Lab which was handed out before we left the class.  The purpose of this lab was to investigate the procedure and results of Rutherford's gold foil experiment and to describe how the findings led tot he rejection of the Thomson atomic model and the emergence of Rutherford's model. 

If you were absent today you can find this lab posted in the Unit 6 handouts folder as well as in the labs/activities folder. 

Our homework for tonight is to

1. Finish the lab from today in class, if you didn't do so already.

2. Complete the 2 WebAssigns that were assigned yesterday-due at 11:59 tonight.

3. Take notes in your journal on the 2 PowerPoints that are posted in the Unit 6 handouts folder. The PowerPoints are labelled "Atomic History Part 1" and "Atomic History Part 2" and will be checked in tomorrow.

4. The Unit 6 Review Packet is due in a week from today so make sure to work on it every night.  Mrs. Friedmann recommends answering 2-3 questions per night so that you can pace yourself. 

The next scribe is Juliette O.

Apps, Tests, and Unit 6

Apps

To begin the day, Ms. Freidmann shared with us a secret weapon on how to study smart. Use Cold Turkey! This is an app that will, when activated, shut you out of all your social media sites for the amount of time you want. This enables you to work hard on studying without the constant distractions of Facebook, Instagram, Tumblr, etc. I know that you are eager to get this app so I posted the URL right below so you can start eliminating your distractions right away.

http://getcoldturkey.com/

Tests

Today we recieved two things, the silver nitrate lab and our tests. If you did not take the test, make sure to talk to Ms. Friedmann as soon as you can. Before we started to talk about the content of the test, Ms. Friedmann wanted to share with us her perspective of the tests. Going into the test, Ms. Friedmann anticipated that the test scores would be fairly high because we demonstrated that we knew the information pretty well in class. Also she made a practice quiz, video, and worksheets to ensure that we had ample amounts of study material. However, when she got the test scores back, they were not as high as anticipated. This is when she stopped and had to rethink what was still causing the grades to be low. She was able to come to a conclusion based off of the book David and Goliath by Malcolm Gladwell (which she highly recommends any of his work.) In his book, David outlines how the difficulty of parenting is affected by finances. It is reasonable that when you are poor, parenting is difficult due to the lack of food, shelter, etc. As more money is given to the parents, parenting becomes substantially easier. However, when the family starts having more than 75,000 dollars as an annual income, parenting becomes more challenging again. This is because children do not want to listen to their parents, work hard, or get good grades because they know they have enough money that they will never have to work. Ms. Friedmann feels that this is where she is. When we look at the video, we look at what we got wrong and move on. We never truly take enough time to understand the answer. Due to this, she will NOT be making a video this unit. She wants us to study smart! She wants us all to know that this in NO way is a punishment. This is simply an experiment to see how this new approach affects our grades on the Unit 6 test.


Malcolm Gladwell

Unit 6

The two power points are apart of the homework for tonight. They can be found in the Unit 6 handouts folder. You can copy these notes in your journal,  BUT make sure to add on to them because we did not get through all of both power points. Here are the notes we took today:

I. The Atom
    1. we will be studying the history of the atom and the current understanding of the atom
    2. atoms are not visible
    3. The Greek Philosophers
        a. they were the first people to think that stuff is made out of stuff
        b. they would talk about their understanding (not experiment)
        c. came up with the conclusion that earth, air, fire, and H2O made up 'stuff'
        d. Democritus and Leucippus
            1. you divide things and get smaller things
            2. everything is made up of smaller things of that same thing. For example, flame is made up of  million of tiny flames all combined to make one big flame.
II. The Greek Model
    1. Democritus
        a. he came up with the idea that the smallest thing of matter was indivisible or "atomos" in Greek
        b. he did not believe in subatomic particles- or that the atom can be divided. We now know that the atom can be divided, however it is made up of the same components (nothing new) so it remains the atom.
III. Alchemy
    1. Started in the dark ages
    2. People thought that they could take cheap metals and find a way to react the cheap metals together to make gold
        a. they did not succeed yet figured out many new metals through their experiments
    3. they found phosphorous because they believed that anything yellow could be boiled down to make gold, so they tried boiling down urine and discovered phosphorus!
IV. Robert Boyle
    1. This is where we ended our notes, however, Ms. Friedmann did recommend a video posted in the unit six box to help further our understanding about Robert Boyle.
        
Democritus                                        Lucippus

    
    Boyle

Homework/ Reminders

Reminders:
1. Make sure to print out the calendar, the two objectives sheets, section 2.1-2.2 reading sheets, and the unit 6 review packet.

Homework:
1. Pick a few questions in the review packet to go over and try them. Just get the juices flowing about the topic. This packet will be due on Wednesday December 11.
2. Two webassigns are due tomorrow night at 11:59 pm.
3. In the unit 6 handouts folder, click on the power points 12.3 Atomic History Part One AND Part Two and take notes. Due Thursday because Ms. Friedmann will be absent tomorrow.

Molecular Mass of a Gas Lab

Mrs. Friedmann began class by checking our procedures/data tables that we prepared over Thanksgiving break for the lab test today. We'll be getting our Unit 5 tests back tomorrow because she wanted to give us plenty of time to complete the lab.

Introduction:

Using whatever lab equipment necessary, we were supposed to determine the molecular mass of our gas (Butane) which was contained in a lighter. Butane's insoluble in water, so, using water displacement we could collect it in a eudiometer and solve using Dalton's Law of Partial Pressures (to account for the water vapor) and the Ideal Gas Law.

Procedure:

1. Gather one gas eudiometer with stand, one large beaker, and one Butane lighter
2. Measure and record the mass of your lighter
3. Fill the large beaker with tap water and take its temperature (record the temp.)
4. Record the barometric pressure for the day
5. Completely fill the eudiometer with room temperature water. Place finger over the mouth and flip it, then insert it into tap water in beaker. ONLY REMOVE YOUR FINGER ONCE IT'S UNDERWATER
(No air bubbles)
6.  Now, carefully bring the lighter underwater - beneath the opening of the eudiometer - and depress the lever on the lighter. This will release the Butane gas into the eudiometer and it should bubble all the way up the tube. Hold the lever down long enough to collect a significant amount of Butane but DO NOT GO PAST 48 mL! You will have to start over if you do.
7. Adjust the height of the eudiometer until the level of water inside the eudiometer is the same as the water
level in the beaker. Now the pressure in the eudiometer should be the same as the atmospheric pressure.
8. Record the volume level of the Butane gas
9. Dry the lighter off and weigh. Record new mass.
10. Clean up!

Calculations:

1. Calculate the mass of gas that went into the eudiometer.

2. The gas in the eudiometer is a mixture of butane and water vapor. Dalton’s Law allows you to calculate just the pressure of the butane.
Ptotal = Patmosphere = Pbutane + Pwater vapor

3. Calculate the moles of gas collected (n) using the ideal gas equation (PV=nRT)

4. Now you can calculate the molecular mass of the gas (g/mol)

Data:

Mass of lighter before: 12.15g
Mass of lighter after: 12.07g
Water temperature: 20.2 C
Barometric pressure: 757 mmHg
Volume of gas: 23.5 mL
Vapor pressure of water: 17.769 mmHg
Pressure of Butane: 739.231 mmHg


The next blogger's Katie Coy (I think)

Gases Lab Test

Hello, I hope you all had a nice break. I was wondering if you guys had any ideas for the gases lab test--I feel like we're supposed to use a eudiometer like we did for the last lab, but I can't figure out how to get the mystery gas from the tank to the eudiometer. Does anyone know how to solve this or have any better ideas?

Partner Quiz and Review

Hey everyone!

Today in class, we went over the worksheet we had for homework over the weekend.  The answers to 'Gas Stoichiometry 1' worksheet are..

1. 2.3 L of H2
2. C3H8  + 5O2 ---> 3CO2 + 4H2O and 22.7 L of CO2
3. 2KClO3 ---> 3O2 + 2KCl and 0.12 g KClO3

As Mrs. Friedmann stated in class, there will be a study session tomorrow morning at 7am for all those who would like to attend.  Don't forget to bring a charged calculator for the test tomorrow!!  The video going over the study packet is now in the Unit 5 box.

 We also took a partner quiz that we are now able to use for studying purposes.  Hope everyone did a good job! :) The key to this quiz is in the Unit 5 Keys folder- so don't forget to take a look at that too.

 
Good luck studying everyone! 

Molar Volume Lab and Gas Stoich

Hello My Fellow Classmates!


Homework for the Weekend:

- Finish the Molar Volume Lab for Monday
- Complete Gas Stoich Worksheets (under Unit 5 Handouts)
- Continue studying for the Unit 5 Test on Tuesday by working on the Review Packet!

In class, we discussed a lot about the stoichiometry that is involved with finding molar volumes and gas pressures. We also talked more about STP (Standard Temperature and Pressure). You can find the notes on these topics in the Unit 5 section under Unit 5 notes!

Question of the Day:

Jordan asked a very great question in class on Friday and we had a demonstration that displayed some of it.

"Does a gas ever exert no/0 pressure?"

Mrs. Friedmann explained that all gases will exert some pressure, but never 0. This is because particles in gases are constantly moving and bouncing off of one another as well as surroundings. This is what defines a gas. In order to have 0 pressure, the particles would have to stop moving altogether. If the particles stopped moving, they wouldn't form a gas anymore. A gas at "Absolute 0" wouldn't be a gas, but a solid.

Overall, Study tons and tons for the test!

Next Scribe: Elayna M. :)

Lab: Molar Volume

Post Author: Georgia A. 

Homework:

1) 2 WebAssigns are due tonight @ 11:59pm 

2) Watch the video going over the prelab problems for the lab you did today, and take notes (check in tomorrow).  The write-up for this lab is due Monday, 11/25.

3) Print out a copy of the Unit 5 Review Packet (in the Unit 5 Handouts folder) and start work on it tonight!  Our unit test is on Tuesday, 11/26.

4) If you were uncertain about the manometer calculations you did for homework last night, check your work against the key posted in the Unit 5 Keys folder

Lab

Background and Purpose:

The "molar volume" of a gas is the amount of space one mole of a gas occupies at Standard Temperature (0℃) and Standard Pressure (1.0 atm). Standard Temperature and Pressure are abbreviated "STP." As it turns out, this number is always the same: one mole of gas (ANY gas) at STP always occupies 22.4 litters. In this lab you will attempt to demonstrate this fact. 

Pre-Lab Questions:

Reaction of 0.0285 g of magnesium with excess hydrochloric acid generated 31.0 mL of hydrogen gas. The gas was collected by water displacement in a 22.0℃ water bath. The barometric pressure in the lab was 746.4 mmHg. 

1. Use Dalton's law and the vapor pressure of water at 22.0℃ to calculate the partial pressure of hydrogen gas in the tube. 

2. Use the Combined Gas Law to calculate the corrected volume of hydrogen at STP

3. What is the theoretical number of moles of hydrogen that can be produced from 0.0285 g of Mg?

4. Divide the corrected volume of hydrogen by the theoretical number of moles of hydrogen to calculate the molar volume of hydrogen at STP.

Lab Write-up

1. Title

2. Purpose 

3. Data

4. Calculations: Use data from both trials 

       a. Write and balance the reaction between magnesium and hydrochloric acid

       b. Calculate the mass of magnesium and then calculate the moles of magnesium for each of the two trials (Recall that 1.00 cm of magnesium ribbon has a mass of 0.01085 grams)

       c. Using stoichiometry, calculate the moles of H2 produced for each trial.

       d. Using Dalton's Law of Partial Pressures, calculate the pressure of the H2 gas in the eudiometer for each trial.

       e. Using the Combined Gas Law, calculate the volume of the H2 gas at STP for each trial.

       f. Calculate the molar volume of a gas at STP for each trial. Average the two molar volumes to get the final molar volume you will report in your conclusion

       g. Calculate the percent error of your reported molar volume.

       h. In setting up this experiment, a student noticed that a bubble of air leaked into the eudiometer. What effect would this have on the measured volume of a hydrogen gas? Would the calculated molar volume of hydrogen be too high or low? 

Conclusion

a. Claim - state here what you found the molar volume of the hydrogen gas to be.

b. Evidence - What data led you to this conclusion? Talk through the logical steps that led you from the data you measured in class to the claim stated above.

c. Reasoning - How close were you to the actual molar volume of a gas? What was your percent error? What SPECIFIC mistakes in the lab could have caused the error in your results? 

Data:

Observations: 

 It starts bubbling from the Magnesium and Copper at the bottom of the eudiometer. Bubbles rush faster as time progresses. The gas is pushing the H2O out of the rubber stopper. A space full of Hydrogen gas starts forming at the top. 

Next Author: Pamela H. 

More About Gases

Homework:

We started off class going over homework from the night before (the 2 gas problems worksheets), and then Mrs. Friedmann handed back the Gas Variables packet that the class did on Friday which we're supposed to go over by ourselves tonight. You should correct it using the key posted in Unit 5 Keys folder on Moodle. The other homework tonight is a small worksheet about pressure, and we don't have to do the 2 worksheets with Manometer problems! :)

In Class:
We started off with a lecture on Flexible vs. Inflexible Containers:

Flexible Containers: 
example: a balloon          
                                           
-pressure stays constant                                                  
-volume changes

Inflexible Container: 
example: metal tank

-volume stays the same
-pressure changes

Then Mrs. Friedmann introduced Direct and Indirect/Inverse Relationships to us:

A direct relationship is when one property/value increases the other increases too. Or if it decreases, the other one decreases as well.
An indirect relationship is when one property/value increases and the other decreases or vice versa.

So in applying this to the Ideal Gas Law (PV=nRT), when you solve for the constant R by writing R=PV/nT it's useful to know that PV (and other variables next to each other) have an inverse/indirect relationship while variables that are on top of each other like V/T have a direct relationship.


And that's it as far as lecturing goes! For the rest of the day we just did some really cool demos!

Liquid Nitrogen Demo:
We'd all been wondering what was up with the small styrofoam container in the corner pouring what looked like steam for a good part of the class, so when Mrs. Friedmann pulled it out we were all pretty anxious to see what it was exactly. What we definitely weren't expecting was for Mrs. Friedmann to pull out 15 inflated balloons from the 6 inch wide, 6 inch long container. Turns out, it was filled with a substance called liquid nitrogen which can freeze pretty much about anything almost instantly, including Peter Dales backpack. Thankfully, he remembered to take his chromebook out beforehand, but he probably had an interesting time trying to bite into his sandwich during lunch.

THIS IS NOT A GOOD IDEA


Liquid Oxygen:
Mrs. Friedmann gave us a quick demo on liquid oxygen, too. Apparently, liquid oxygen is very powerful oxidizing agent and can ignite quickly from very small sources of heat. This was demonstrated when Mrs. Friedmann collected a small amount of it into a test tube and inserted a small stick with a single spark at the tip into the tube. The spark ignited, and there was a brief flare.

The Combined Gas Law

Answers to Yesterday's Homework

First thing in class today Mrs. Friedmann checked in our homework and went over the answers. The answers are as follows:

1) .75 L
2) 27 degrees Celsius
3) .12 moles
4) a) .021 moles
    b) 120 g/mole (divide the mass of freon by the number of moles of freon)
5) .0560 moles
6) 240 K or -33 degrees Celsius (either would be acceptable)
7) 58.1 moles
8) 1.88 moles
9) 3.42 minutes (this problem was just for fun and will not be on any exams)
    Work: 1.72 * 10^-4 moles O2 * 1 h             * 1000007 cockroaches = 2.01 moles O2
               1 cockroach * h               60 minutes

Combined Gas Law Notes

Next, we took notes on the combined gas law. Mrs. Fridmann's notes can be found here: http://gbs-moodle.glenbrook225.org/moodle/file.php/12015/1314_Unit_5/Unit_5_Notes/11.18_Class_Notes.pdf

Chemistry Demos

Finally, at the end of class we watched Ms. Friedmann show us some neat chemistry demos. It's too bad if you missed them, but (like videos of farting cats and Hollywood celebrities) they can both be found on the internet.

Homework

Tonight's homework is the "Gas Laws" handouts. We did the first one in class. It looks like this:

Good luck and have a good night!

The next blogger will be Lauren B.

The Gas Unit

Gasses, and more Gasses

Recap of Friday November 15,

• Received a packet on properties of gasses
• Completed the packet with partners
• Had two tape-in worksheets assigned

Explanation:

The substitute handed out a review packet on the behavior of gasses which you can find in the handouts section under Unit 5 on moodle. The packet was due at the end of class, and if you finished you were to begin the homework which was two pages in your journal.

Homework:

• Two worksheets in your notebook

 Next Scribe: Brandon Moy

Return of the Tests!

The test grades are out!

Here is what we did today (11/14/13)

• Got back the tests
• Went over any questions needed
• Discovered some fantastic failures

Explanations

Mrs. Friedmann handed out the tests today, and stating that there was an unexpected amount of great failures. Each student had a chance to ask about a question, row by row. We clarified Net Ionic Equations and the limiting reaction equation on the free response. Mrs. Friedmann also said that any students who put A for question 14 would get the point since it was unclear what the actual answer was. That raised some of the students grades up.

Homework

Since the day was full of review of the test there wasn't much to write about. Mrs. Friedmann assigned a ChemThink along with notes that are due tomorrow. You were also supposed to watch the Youtube Video of Mr. Arum Majumdar as he will be coming to speak with us next Thurdsay. You are to write a question on a notecard to him, addressed with your name, Mrs. Friedmann's name, and with your period (5). 

If you cant find the video on moodle here it is:

Best wishes to Mrs. Friedmann and her mom!

I will be doing tomorrow's blog as well.

Colligative Properties

Video:
We started off the class with a video on soda slushies. Later in the class we learned why this works.

Colligative property notes:
These kind of properties are physical properties of solutions that depend on how many solute particles are present, NOT on what the solute is.

Aqueous solution equations:
molecular- C6H12O6(s) ---> C6H12O6(aq) 1 mole particles
ionic- NaCl(s)---->Na+(aq) + Cl-(aq)  2 moles particles

This is why ionic compounds are more effective for colligative properties.

Two colligative properties:
The two main properties will focus on are Boiling Point Elevation and Freezing Point Depression.

Boiling Point:
The ions of a solute block the water from escaping. The water requires more energy to escape the container and so the boiling point is raised.

Freezing Point:
When a solid is formed, it can be thought of a crystal forming. More solute in a solution makes the formation of these crystals require more energy. Thus, the freezing point is lowered.

Solubility of Solids v. Gases:
As we as learned, a solid's solubility is increased when the temperature is increased. With gases however, the solubility decreases with an increase in temperature. Another way to affect the solubility of gases is with pressure. By increasing the pressure of a gas, the solubility increases.

Also, I'm sorry that this is late.

The next scribe is:
Daniel W.

Where's our November 12 post?  On the lesson on colligative properties, the day before the test?  Colin?

Molarity & Stoichiometry Review

Scribe Post Author: Serene P.

11/8/13

To begin class today, Ms. Friedmann checked our previous night's homework assignments. Then, she informed us of our homework over the weekend.

1) Unit 4 Test has been moved to Wednesday!

-A study session will be held Wednesday morning at 7 am

- A review packet was given and a set of extra precipitation stoich problems (however, these are optional preparation items for the test)

2) Read sections 10.3 and 10.4 in your textbook and take notes in your journal-due Tuesday

-You need to know about Colligative Properties for the test, but you do not need to know how to calculate freezing point depression, boiling point elevation, or osmotic pressure.

3) WebAssign 10.3-due Monday night at 11:59 pm

During class, we also picked up a sheet titled, "Chemistry Scene Investigation~Trouble in the Chemistry Store Room." However, we were not able to get to this activity.

We went over the two homework sheets. Ms. Friedmann demonstrated how to do question 2a on the homework sheet titled 'Molarity.' Here is the work for the question:

2) What is the molarity of each ion present in aqueous solutions prepared by dissolving 15.00g of the following compounds in water to make 5.25 L of solution?

a) magnesium bromide?

15.00g MgBr2 x 1 mole MgBr2 = 0.08148 moles MgBr2

                        184.10g MgBr2   

0.08148 moles MgBr2   = 0.0155 M MgBr2 ←overall chemical molarity

5.25 L Solution        

Chemical concentration x number of particles

So…

0.0155 x 1M Mg2+ ions = 0.0155M

0.0155 x 2M Br- ions = 0.031 M

If you want the total ion concentration, do 0.0155 x 3 = 0.0465M

For question one of the ‘Molarity’ worksheet, the answer was 6.46M NH3. The work is shown below:

11.0g NH3 x 1 mole NH3  = 0.64554 moles NH3

                   17.04g NH3

100 mL x 1 L       = 0.1 L

            1000mL

0.64554 moles NH3  = 6.46 M NH3   

0.1 L NH3                     

       

On the ‘Concentration and Solution Stoichiometry’ sheet, the answer for question one should have been 0.519 M NaOH. To solve this question, you should have done the total number moles in solution divided by the total volume of the solution. The answer was a little closer to the higher molarity.

For question two on this worksheet, the answer was that both reactants were used up equally. There was not any limiting reactant because the amount that resulted from both Pb(NO3)2 and KI was 0.0875g PbI2.

The remaining answers for questions 2b, 2c, and 3 on the ‘Molarity’ worksheet will be found on the key that should be posted on moodle.

Ms. Friedmann also discussed the differences of molecular compounds and ionic compounds getting dissolved in water. She explained that the ionic compounds will be able to split into more particles when dissolved in water. This is because the water molecules will be able to attach to the ends of particles with opposing charges. An example is MgBr2.

Ionic compounds are able to conduct electricity as well.

However, molecular compounds in water will act differently. They will not conduct electricity and will not break apart. One particle of the compound will become one particle in solution. However, from being a solid, the compound will be referred to as aqueous because water gets in between molecules of the compound. It will separate molecules of the compound, not ions. Ionic compounds will separate into ions when in solution.

We also learned how colligative properties depend on the number of particles in solution. Water boils at a higher temperature when particles are added. Particles with charges that hold onto water molecules keep them from escaping into a gaseous state. Therefore, you must increase the heat energy to reach the boiling point of the water(boiling point elevation). If there is a lot of solute present, the water can boil at a temperature higher than a 100 degrees.

At the end of class, we had some fun with Georgia’s large hot pack.

The next scribe post author will be Colin S.