Thursday, March 24, 2011
Remember, tomorrow is the last day of the quarter and our Thermochemistry test is tomorrow!
Below are the answers to the Unit 10 Chemistry Practice packet, we didn't have to do the first two pages of the packet (math skills and reading for information).
Our homework for tonight is to study for tomorrow's test. Also, make sure all the pages in your journal are finished!
Wednesday, March 23, 2011
Today we started class by doing the Combustion Lab as a class. This lab's main question was: How much energy is released in the burning of candle wax? To figure this out, we measured and massed 100 ml of water in a beaker and then placed it over a small, burning candle underneath. Before we placed it above the burning candle, we massed the burning candle. We waited for the candle to heat up the beaker a little bit before taking the water's temperature again and then massing the candle one more time. Once we concurred that the mass went down because some of the wax had changed because of the reaction that took place (Wax + O2 -> CO2 + H2O + Heat), we were then able to plug our data into our formula (Heat = mc [delta] T).
Tuesday, March 22, 2011
1. The first thing we did today in class was get journal pages 5 and 6. The bottom picture is page5 and the top picture is page 6.
2. The next activity we did was go over the Heat Fusion Lab. If you were not hear within the last few days of class, you can get the pages from the previous blog. We first discussed what happened to the water and ice during this experiment. The ice was menting in the water. Two things happened in the cup:
1. Ice melted
2. The water was getting colder
In this experiment, we looked at what the endothermic and exothermic items were. The endothermic, or the process that gains heat, was the ice. As the ice was being stirred in the water, the ice was absorbing heat and making the ice colder. The exothermic, or process that losses heat, is the water because it is losing heat. Mr. Tucker drew us a picture of a glass with one ice cube in it. He then drew and arrow, coming from the water, to the ice cube. this shows the process that occurred in the experiment. The ice absorbed the heat coming from the water which caused the ice to melt and the water to lower in temperature. This picture also shows us how the ice is endothermic and the water is exothermic.
We also discussed the important notification that HEAT LOST = HEAT GAINED. The equation for this is M x C x delta T (Tf-Ti) = M x Hf (Heat of fusion).
3. The next thing we did was look at the data table from the experiment. We only did one trial for the experiment, so don't do trial 2. Our data that we got is as follows:
Mass of dry calorimeter: 4.02 g
Mass of calorimeter and water: 97.6 g (should be close to 100)
Initial Temp. of water: 23 degrees Celsius
Final Temp. of water: 4 degrees Celsius
Mass of calorimeter and water after ice melted: 121.23 g
4. We then began doing the Heat of Fusion Lab Calculations and Questions.
1. Find the mass of the original amount of water in the calorimeter. 97.60 g H2O(l)
2. Find the mass of the water resulting from the melted ice. 23.63 g H2O(s)
3. Find the change of temperature of the water. 19 degrees Celcius
4. Find the amount of heat lost by the original amount of water when it cooled. (specific heat of water is 4.18 J/g C)
97.60 g x 4.18J/ g C x 19 C = 7751.39 J sig figs! So the answer is 7751 J
5. Find Heat of Fusion for the ice. 7751 J= 23.63 g x Hf. Divide both sides by 23.63 g =328 J/G
6. Skip this problem
1. Is the process of ice melting endothermic or exothermic? Heat goes into the ice cube, so endothermic
2. Is the process of ice freezing endothermic or exothermic? Since heat leaves the ice, making it freeze, it is exothermic
3. Compare your heat of fusion to that in your notes? Ours is 328 J/G and the real heat of fusion is 334 J/G.
5. After reviewing the lab, we began to do page 5 and our new lesson for the day, ENERGY STOICH. Above were the journal pages so look back to those for the problems. We did problems 1 and 6 together so that is what I am going to show you how to do.
Monday, March 21, 2011
this quiz was 15 points and can be made up by Thursday.
The Unit Eleven test is on Friday March, 15th, so if you will be gone on that day for Spring Break, Mr. Tucker strongly suggests you take it before Spring break.
Finally, for the last five minutes of class, we went back to our lab tables and began the lab by heating the water that was initially 50 degrees Our homework for tonight is page 4 Heat Calculations 3 that we picked up in the beginning of class.
Saturday, March 19, 2011
Today we went to the auditorium for chemday to watch an episode of MythBusters called Crimes and Myth-Demeanors 2.
The teachers handed out a paper with the questions related to the show.
Here are the following questions:
1. The fingerprint lock is an optical sensor.
2. What do Jamie and Andy have to do in order to break into Grant’s lock?
They need Grants fingerprint.
3. Which method of lifting prints works?
They added powder to the glue print.
4. Why doesn’t the paper print work?
It’s not three- dimensional.
5. In thermal motion alarms, what sets off the alarm?
6. Why did Tory set off the alarm?
His body heat was picked up by the alarm.
7. What problems are involved with using a CO2 extinguisher to cool Tory?
It would be difficult to have a consistent temperature in the body because it’s just going to be a blast. So he can just heat it right back up in the middle of the room. Also it is dangerous can it can cause frostbite.
8. Which material was more like human skin? Did it work?
They use a Ballistics gel. But no it didn’t work because the ridges are not deep enough.
9. Was the Team able to covertly get Grant’s fingerprint?
Yes, Carrie is able to get Grant’s fingerprint by using a cd case.
10. Why does the second print work?
The lines of the fingerprints are clearer.
11. Why did the neoprene suit set off the alarm?
The longer Tory wears the suit the heat from his body is transferred in the suit.
12. Did the Predators method of pasting yourself with mud fool the alarm?
No, because the body heat warmed up the mud. Also there are mud tracks left.
13. How did Adam’s fingerprint work?
They made a latex copy that is planted on his heated thumb and then he licked it.
14. What happened with the photocopy print?
They are able to get in.
15. What happened when they increased the room temperature?
A huge hot stream is flowing in the room setting off the alarm.
16. Did a near naked Grant fool the alarm?
No, because the alarm is just too sensitive.
17. How does the big pane of glass work?
The glass can block the infrared of the body.
18. Did the glass method work?
19. What is glass- re- locker?
A pane of breakable glass within the safe itself that if broken activates locks that makes the door impenetrable.
20. How many milliliters of nitroglycerine does Adam think he needs?
140 ml of nitroglycerine
21. Where are they testing the safe?
They are doing their test at a sewage plant.
22. How big is the glass in the actual safe?
The size is a small glass in the middle of the safe.
23. What are the five steps to blow up the safe?
Step 1, is to bore a hole in the top of the safe with a thermo lance. Step 2, is to fill the safe with water. Step 3 is to lower explosives into the safe. Step 4 is to blow the door of the safe and step 5 is to get the money and run.
24. What was the problem when they burned a hole in the safe?
It also burned everything in the safe.
25. How does the ultrasonic motion detection work?
It sets out a very high frequency sound wave which bounces off in all the wall of the room and comes back to the sensor to create a pattern.
26. What material soaks up the sound?
A thick rug.
27. Does Carrie’s bird suit work?
No it didn’t.
28. Does the bed sheet work? Why?
Yes, because the bed sheet is actually absorbing the sound wave.
29. What was the last method used to fool the alarm? Why does it work?
The last method is to slowly walk in the room. This method worked because the sensor has a threshold level of movement that needs to trigger it.
30. Were Adam and Jamie even able to copy the safe breaking Crime?
REMEMBER THE HW ON THERMOCHEMISTRY WHICH WE WILL GO OVER ON MONDAY.
Thursday, March 17, 2011
- Temperature : Average kinetic energy of the particles in a substance(oC,oF,K). oF is out because we are not going to use it.
-Heat is transfer of energy(Joules)
Endothermic:something gains heat
Exothermic - something loses heat.
-For oC, H2O is always 4.18
- Then, we went over couple of problems which is about THermochemistry.
- This is the homework.
Wednesday, March 16, 2011
Friday, March 11, 2011
if reaction shifts left, then NO2 and O2 increase and NO3 decreases on the graph
the opposite of decrease temp in INCREASE TEMP so shift left towards the heat
Decrease H2- shift left
Add a catalyst…… skip, do not worry
Increase volume…..skip, do not worry
a) True, if K is greater than 1 the products are favored (K = P/R)
15. First, find the concentrations of all substances by dividing mols by 5L
From top left to right
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.
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
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
f) mol / L
g) NOBr- 0.182M, NO- 0.0667M, Br2- 0.0125M
h) K= 0.00168
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
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
Wednesday, March 9, 2011
Today, we started Chemistry by taking four jurnal sheetes. The sheetes included:
- Frayer Charts
- Equilibrium notes
- Jurnal Sheet nr. 4 - Le Chatelier 1
- Jurnal Sheet nr. 12 - Equilibrium 2
Mr. Tucker has begin class with reminding us that he will not be in school on Thursday March 10 and Friday March 11, so we have two days for review for TEST on Monday March 14, 2011.
Next we and Mr.Tucker read pages from our textbook (549 - 550), Chapter 18 Section 2. The text was about Reversible Reactions and Eequilibrium. Now we know that a reversible reaction is one in which the conversion of reactants to products and the conversion of products to reactants occur simultaneously.
2SO2 (g) + O2 (g) <------> 2SO3 (g)
After reading Mr. Tucker gave us few minutes to fill up Frayer charts. We were suposed to write our definition, picture, non- examples and examples of EQ (equlibrium). Then our chemistry teacher explained to the class what is equlibrium.
Equlibrium is a revesible reaction in whichconcentration of reactants + products are constant. Equilibrium is only for gases (g) and substances which soluble in water (aq).
The Equilibrium can be measured:
Keq = [products] / [reactants]  - stands for M
Homework:Jurnal page 4 and questions 1,2 and 4 from page 12
Tuesday, March 8, 2011
Thursday, March 3, 2011
WE JUST WROTE THIS LAB IN OUR JOURNALS!!
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.
1/2 tablet- 14sec
1 tablet- 6sec
Conclusion: As concentration increases, so does the speed of the reaction
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!)
1/2 tablet - 16sec
1/2 tablet crushed- 5sec
Conclusion: As surface area increases, so does the speed of the reaction
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.
5C- 2min, 20sec
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.