Thursday, March 24th 2011- Emma N.

Today when we came into class, we picked up two sheets titles "Thermochemistry Review" on the front table. Everybody who brought food for our food review day placed it on the back table, and taped their write ups about it above the food.

Mr. Tucker then stamped everyones homework- the Unit 10 chemistry practice. If you completed the 3 pages required (not the math or reading pages) then you received 3 stamps.

Next, we went over answers and asked questions while eating our delicious food, that our fellow classmates brought in for us. (see pictures above for part of homework)

Once we finished going over the chemistry practice, Mr. Tucker reviewed Energy Diagrams vs Heating curves. It is important to know that energy diagrams relate to endo/exothermic reactions. Exothermic reactions release heat, and endothermic reactions gain heat. (see pictures above)

After that, he handed out 2 sheets: "Thermochemistry Review"

And told us to STUDY FOR THE TEST!!

Tue, 3/22,Eman

Today we entered class with two sheets waiting to be picked up on the front desk. Two sheets titled Energy and Reactions 1. After grabbing those two sheets and taking a seat, Mr. Tucker had gone around and stamped the homework from the night before. Once that was done, he had gone over some problems from the night before. Here are some answers that we went over class (they might vary):

CALCULATIONS

1. Mass of original water
            101.66 g.
2. Mass of water from melted ice (subtract mass of ice in water from the original water)
            17.71 g.
3. Change in temperature of water
            13 degrees Celsius
4. Amount of heat lost by original
            5,524.2 J.
5. Heat Fusion for the Ice
            311.914 J/g

QUESTIONS

1.Is the process of the ice melting endothermic or exothermic?
            Endothermic. Heat is traveling on/into the ice.
2.Is the process of the ice freezing endothermic or exothermic?
            Exothermic. The energy is traveling out of the ice.
SKIP #3

            We then continued on to the worksheets we had picked up in class. We had done #1 a & b in class. These are the answers we got as a class for that sheet:

1. CH4 + 2o2 -> CO2 +2H2O
   a. 4.00 g of Methane (CH4) is allowed to burn according to the reaction above. The energy released by the reaction is used to head 800 grams of water from 15.0 degrees Celsius to 81 degrees Celsius.
            -Find the energy released by the reaction in kJ.
            800g x 4.18J/gºC x 66.4ºC = (app.) 222 kJ
            -Find the moles of CH4 burned.
            4.0g CH4 x 1mol/16.04g = .249 mol CH4
            -Find Delta H in kJ/mol (including the sign) for the reaction above.
            222kJ/.249 mols = 892 kj/mols

** remember  delta H (which is heat associated with reaction)/ 892 kj/mol
  
   b. In another experiment 1.55 g of CH4 is burned. How much energy would be released?
            1.55 g CH4 x 1 mol CH4/16.04 g CH4 x 892 kJ/1 mol CH4 = 86.197 KJ -> 86.2 kJ

By the time we had gone over these problems in class, we were instructed to finish the rest of the two sheets for homework!

Michelle - Monday March, 21

Today started out by picking up 2 sheets at the front of the room for the Heat of Fusion Lab. Then Mr. Tucker checked in the homework which was page 2 of Heat Calculations 2 and answered questions that the class had on it. After that we took a short quiz on thermochemistry that was similar to the notes we previously took in class on thermochemistry and the homework page.
Finally we conducted the Heat of Fusions Lab. The procedure to conduct the lab can be found on the journal page he handed to us in class. It looks like this.

While conducting the experiment we had to write down the lab data in our journals. Our lab group's data looked like this.

After filling out the data page, Mr. Tucker had us fill out questions 1-3 on the 2nd page of the Heat of Fusion Lab. In order to fill out these questions, the data be filled out. The numbers from our calculations can be found on the data page. Our calculations looked like this.

Lastly, Mr. Tucker handed out journal page 4, Heat Calculations 3 for homework. Journal page 4 and the Webassign are due tomorrow.

Andrew- Friday, March 18th, Chem Day

Today for class we went to the auditorium to watch Mythbusters for a chem day. The Mythbusters episode was called "Crime & Mythdemeaners" and had to do with different security systems. We had to fill out a sheet with 30 questions having to do with the video.

The first part of the episode had to do with a fingerprint lock. They tried different methods of copying a fingerprint in order to trick the fingerprint lock. One of the questions we had to answer was:

What material was most like human skin?

Ballistic Gel

Ballistic gel was used to make a fingerprint very similar to a human fingerprint so they could fool the sensor on the door.

The second part of the mythbusters episode had to do with thermal motion alarms. Thermal motion alarms take an average room temperature reading, and are set off when the temperature is changed by the presence of a person.

The third part of the mythbusters episode tested out an ultrasonic motion detector. The motion detector is set off when someone walks past it. The mythbusters thought that if the person is undetectable than the alarm would not go off. They tested this theory by having someone walk through the room with a big white sheet over them, and the alarm did not go off.

In the final part of the mythbusters episode the final myth had to do with filling up a safe with water than dropping an explosive with nitroglycerin into it making the door fly off with a huge explosion. This myth came from a movie where this was done, and the villain got away with the goods inside. After numerous failed attempts the mythbusters finally got everything to work our just how they wanted. At the end they finally dropped the explosive into the water like the movie, and a huge explosion made the door go flying. Everything on the inside of the safe was destroyed though so the movie was not too realistic.

Thursday, March 17th ( St. Patrick's Day)

Today in class, besides Mr.Tucker's cheesy jokes that he thinks are great, We took notes on Thermochemistry/Energy.

Here are the notes:
1. Temperature-

Average kinetic energy of the particles in a substance.

Units Used: Fahrenheit( we don't use this in class), Celsius and Kalvin.

2. Heat-

Transfer of Energy (joules).........Can be gained or lost.

Tuckers Joke: " There's also dominicks and walgreens".....yaaaa? no comment

3. Heat loss and Gain

Endothermic- Gaining heat

Exothermic- Loosing Heat.


In between notes we did a quick observation of Mr Tuckers " Magic Blocks." One block was wood and one was metal. The wood block was warm, compared to the metal block. After putting a piece of ice on both blocks, the ice melted faster on the metal block!! This was all due to the energy transfer.



Graph on page 2 of notes ( at top of blog):

Part1.A Heating and Cooling of a solid

Heat (q)= M * Cp ΔT (Tf-Ti)


Part2B Melting solid <-> Liquid freezing

Heat= M * HF

Part3C Heating/Cooling a Solid

Heat (q)= M * Cp ΔT (Tf-Ti)

Part 4D Boil a liquid <-> Gas condenses

Heat= M * HV ( Heat Vaporization )

Part5E Heating/Cooling a Gas

Heat (q)= M * Cp ΔT (Tf-Ti)

Wednesday 3/16/2011

At the start of class we picked up 3 sheets:

Graph, Pre-Lab Questions, and Lab sheet.

Then Mr. Tucker explained the lab, and checked in our HomeWork.

After that we went back into our lab groups and started working on the lab.

You record your data and follow the lab instructions. Also the rest of the lab and graph sheet for the lab are due for homework.

Fri, Kin./EQ Review / Tucker

Sorry for the late post for Thu...internet issues in hotel.  GOOD LUCK STUDYING THE MATERIAL AND SEE YOU ON MONDAY!!  Mr. Tucker

Kinetics & Equilibrium Review Answers

1.       Particles COLLIDE in the correct orientation and with enough force

2.       As temperature increases particles move faster and collide more often and with more force

3.      Surface area, concentration, and catalysts

4.      Surface area is increased

5.      Decrease temperature, decrease concentration of reactants, decrease surface area…..all would lead to fewer COLLISIONS

6.      The reactions continue at equilibrium….they are just at the same rate.

7.      K=  [H2O]² / [HCl]⁴…….others are not used b/c liquid and solid

8.      0.09M

9.      If O2 is removed the reaction shifts to the LEFT (to add more O2)
if reaction shifts left, then NO2 and O2 increase and NO3 decreases on the graph

10. 

a)       Opposite of remove H2O is ADD H2O so shift left

b)        For this problem, write the word HEAT on the reactant side (left).
  the opposite of decrease temp in INCREASE TEMP so shift left towards the heat

c)      No Shift, SiCl4 is a liquid

d)      Opposite of Remove HCl is ADD HCl, so shift right

e)      When the word pressure is mentioned count the moles of gas on each side of the equation…..2moles gas on left, 4 moles of gas on the right…..Opposite of increase pressure is decrease pressure so go towards the side with fewer moles of gas…..shift left

11.   Increase temp, shift left

Add more S, No shift
Decrease H2-  shift left
Add a catalyst……  skip, do not worry
Increase volume…..skip, do not worry

12.   K = [H2S] / [H2]

13. 
a)  True, if K is greater than 1 the products are favored  (K = P/R)

b)  False, if K is less than 1, the reactants are favored

c)  Temp does not affect K, just concentrations of P and R

14.   

a)  N2(g) + 2H2(g)  à  2NH3(g)

b)  O2(g) + C(s)  à  CO2(g)…….this question is trick, but the C must come from    somewhere and the reason it is excluded from the K equation is b/c it is a solid

15.  First, find the concentrations of all substances by dividing mols by 5L

            [NH3] = 0.40M,  [H2] = 0.60M,  [N2] = 0.20M

        Then, figure out the K equation……K = [NH3] / [N2] x [H2]³

            K=  3.7

Thu, Kin./EQ Practice / Tucker

Chemistry Practice ANSWERS:

Math Skills:
From top left to right
1.  2.22
2.  125
3.  8
4.  1.17E-5
5.  1.33
6.  0.942
7.  10
8.  0.868
9.  7.13E-5

Reading for Information:
a)  about 98.6F, Homeostasis…like hair and shivering
b)  about 98.6F, Homeostasis, like sweating
c)  Yes, body keeps changing in response to external conditions
d)  House heats up, thermostat increases, air conditioner turns on, House cools down, Thermostat decreases, air conditioner turns off
e)  Body changes OPPOSITELY in response to stresses(changes) on it…it tries to fix itself.

Data Interpretation:
a)  Temp, Time
b)  Amounts of A and B
c)  about 1-2seconds
d)  Inverse, as T goes up, time goes down
e)  Cannot predict, A may not react with C

Unit 11 Problems Broken Down:
1.
a.  K=  [P] / [R]
b.  K = [NO2]² x [Br₂] / [NOBr]²c)  NOBr-  109.9g/mol,  NO- 30g/mol, Br2-  159.9g/mol
d)  NOBr-  0.910 mol,  NO- 0.333 mol, Br2- 0.625 mol
e)  5L
f)  mol / L
g)  NOBr-  0.182M,  NO- 0.0667M, Br2-  0.0125M
h)  K=  0.00168

2.
a)  double arrow
b)  forward reaction = reverse reaction, concentrations of reactants and products are constant
c)  +, reactant side…….do not worry, I will always tell you what side the heat is on for now
d)  2mols reactant, 3 mols product
e)  More,  Less
f)  GIVEN
g)  add SO2, right, SO2 and O2, SO3, more moles gas, increase
h)  decrease O2, left, SO3, SO2 and O2, less moles gas, decrease
i)  decrease temp, right, SO2 and O2, SO3, more moles gas, increase
j)  increase pressure, right, SO2 and O2, SO3, more moles gas, increase

Thu, 3/3, Tucker

Today each lab group performed a short lab involving a reaction with alka-seltzer and water.  The reaction produced a gas and when this reaction occured in a flask with a balloon placed over the top of the flask, we were able to time the reaction...how long did it take for the balloon to inflate?  Since different groups investigated different independent variables, we then shared data/conclusions with the class.  The three labs are outlined below:

WE JUST WROTE THIS LAB IN OUR JOURNALS!!

Lab 1:
Procedure:  Place 1/4 alka seltzer tablets in 25ml of water in a 50ml flask and place a balloon over the top of the flask.  Time how long it takes for the balloon to inflate.  Repeat with 1/2 and full tablets.
Data:
1/4tablet-  45sec
1/2 tablet-  14sec
1 tablet-  6sec
Conclusion:  As concentration increases, so does the speed of the reaction

Lab 2:
Preocedure:  Place 1/2 alka seltzer in in 25ml of water in a 50ml flask and place a balloon over the top of the flask.  Time how long it takes for the balloon to inflate.  Repeat with a crushed alka-seltzer (which has more surface area!)
Data:
1/2 tablet -  16sec
1/2 tablet crushed- 5sec
Conclusion:  As surface area increases, so does the speed of the reaction

Lab 3:
Procedure:  Place 1/2 tablet of alka-seltzer in 25ml of room temperature water (22 degreesC) in a 50ml flask and place a balloon over the top of the flask.  Time how long it takes for the balloon to inflate.  Repeat this with 5degreesC water and 50 degreesC water.
Data:
5C- 2min, 20sec
22C-  20sec
50C-  4sec
Conclusion:  As temperature increases, so does the speed of the reaction

The independent variables for the lab were concentration, surface area, and temperature
The dependent varibale for the lab was time / speed of the reaction
The controlled varibales for the lab were the size of flask, type of tablets, and amount of water.