Friday 9.17.10 - Matter Lab

REMINDER: Extra credit packet available in the TLC. Look in the bin for the lab we worked on Friday.



HOMEWORK: Webassign due Monday along with review sheet.



LAB:

We worked on a matter lab. We went from station to station looking at models of different atoms and molecules etc. We had to draw what we saw then write the formula of it. Finally we described it (compound, pure substance, element etc.)

EX: Picture: Formula: Terms:
oo oo ooo, 2N2 +N3, Element, pure substance, molecule

NEW TERM:
diatomic molecules- molecules that will always be in pairs when they are alone

H O N Cl Br I F (sound out the word to remember the elements)

Ex: oxygen (O) will always be O2

Thursday 9,16,2010

Today in the beginning of class Mr Paek made a couple of announcements about the upcoming week, here are the dates:

• chem think is due tomorrow-17/9
• web assign is due Monday-20/9
• Quiz on Monday-20/9

Quiz will be on molecules,atoms,compounds, the quiz will also have like 1 density problem and 1 measuring problem.

• lab test Tuesday-21/9
• test - sometime during the week.

Then Mr Paek explained to us the difference between physical and chemical change:

-physical change: do not affect chemical position.

some chemicals present.

same arrangement of atoms.

-chemical change: alter chemical composition

new chemicals formed

bonds broken and formed

rearrangement of atoms

after we did a chemical and physical changes sheet. we had 17 examples, where we had to decide weather the change is physical or chemical.

-some examples:

snow turning into water= physical change

hammering gold into a thin sheet=physical change

phosphorus burning=chemical change

We then did the physical or chemical stations lab: the lab was really easy we had to go through stations.

examples= in station 1 we had to watch melting candle wax, which was physical change. then burn candle wax and wick, which was a chemical change.

in station 4 we had to add water and food coloring, which was physical change. then melt ice in water which also was physical change.

Tuesday 9.14.2010

Today in class we learned about atomic level pictures. We defined the terms:

• atom - most basic unit of matter
• molecule - group of atoms help together by a chemical bond
• element - made up of single type of atom
• compound - molecule made up of more than one kind of atom

Then we did a couple of problems from the worksheet to furthermore explain the difference of these four terms and learn to distinguish them.



In this problem we had to decide for the each of the atomic level diagrams whether they are elemets or compounds and consisting of either atoms or molecules.

Then we defined two more terms:

• pure substance - all the same
• mixture - has different kinds

To get a better understanding of what these terms we did another problem from the worksheet.



We also learned how to write formulas for atomic level pictures.



After that we practiced drawing the atomic level pictures according to the formulas that were given.

Then we had even more practice with writing the formulas and descriptions for the atomic level pictures and also drawing the atomic level pictures based on the formulas.





Once we were done with everything, we had some time to just talk to other people untill it was time to go to the fall sports assembly.

9.13.2010

Today in class we took the quiz that was supposed to be on Friday but, was switched to today. If you did not take the quiz you can make it up in the test center. After taking the test we went over it shortly and did not have time to go to the writing lab like was planned.

Friday September 10, 2010

Today in class we started off my going over unit conversions on page 11. A problem that we did in class was this, If a glacier flows at a rate of 32.5 feet per year, what is its speed in cm per hour?

1.To start to solve this problem you must put 32.5ft over one year.

2.Then multiply this by 12in over 1 ft and then the feet cancel out.

3.Next multiply 2.54cm over 1in and then the inches cancel out.

4.Then multiply 1year over 365 days, the year will cancel out with the year from the first step of the problem.

5 And finally you multiply 1 day over 24 hours, but to get the answer you have to multiply all the numbers on top and then divide by all of the numbers on the bottom. Once you do that you get .113 and thats your answer.

After we went over conversions, Mr. Paek showed us how to get on Web assign, which is the homework. To get to Web assign go to your moodle account. From there go to chemistry with Mr. Paek, and then press on the Web Assign Link. A quicker way to get there is to just go to Webassign.com. Once you get to Web Assign you sign in. It will say institution and there you put glenbrooksouth.il then your password AND your username will be your id number. Once you get into web assign there are a number of assignments that are all due the day before the test. Most of them we have already learned but some of them we haven't. F0r the web assigns the questions that have more then 2 answers, you get only 2 guesses on. And for the questions with only 2 answers you only have one guess. Once you are done with an assignment you press submit and it will tell you all the questions you got right. During class we went to the computer lab and worked on web assigns for the rest of the period.

Wednesday September 8, 2010

Today in class, we finished our labs working on density that we started yesterday. Next, Mr. Paek showed us a demo by using gas, a special type of soap, and a long stick with fire on the end. He had a volunteer shake and pinch on the tube from where the gas was coming from in order to make the soap from inside the beaker rise into the air as a bubble. Once it did, he poked the stick on fire at the rising bubble and a big burst of flames came from the air.

After the demo, Mr. Paek reviewed with us about finding the density of certain objects, and the ntaught us about using Unit Analysis. This means that the units in the numerator and the denominator cancel out so then another unit used will replace its spot. For example, if we are trying to figure out the number of seconds in 1 day, then we would write out the equation like this: 1 day/1 x 24 hrs/1 day x 60 min/ 1 hr x 60 sec/ 1 min = 24 x 60 x 60= 86,400 sec in 1 day. This works because the units day, hrs, and min cancel out which leave sec as the remaining unit for the final answer.

Since we didn't do so well on the last section of the quiz we took last week, we have a quiz on friday covering the same material. So our only homework for tonight is to study measuring the volume of water in graduated cylinders and note cards, and make sure you make 1 guess.

Tuesday 9.7.10

Today in class, we started off by going over the basics of density (the formula and units of density). The formula for density is . In order to find mass and volume we need to know the units of mass (grams (g), kilograms (kg), and milligrams (mg)) and volume (milliliters (mL), Liters (L) and cm (cubed)). We followed this up with examples of finding density to get a better understanding for the material (Ex: If the mass of a powdered substance is 6.52 kg and the volume is 22.4 L, what is the density? You would then go on to put the mass (6.52kg) over (divide by) volume (22.4 L) and get 6.52kg/22.4L= .291 kg/L, and because it is multiplication, the answer has to match the lowest amount of significant figures, in this case, 3).

We also did an example of the different densities of substances in water and found out the a substance with higher density than all the rest sinks down to the bottom and the substance with less density than all the rest, floats to the top. All the substances in between then order themselves from top to bottom going from least dense to most dense in a totem pole looking fashion. We finished up class with a Density lab. For this lab we needed a regular object, an irregular object, a ruler, a balance and a 10 mL and 100 mL graduated cylinder.

In this lab we found the mass of a regular solid object (a metal rectangular prism) using the balance to "mass" it and the volume using the formula of Length x Width x Height. We then used these measurements to calculate the density of the solid using the equation .

To then find the density of an irregular solid object (a metal nail) we measured the mass using a balance. To get the volume we filled a 100mL graduated cylinder about half full of water. Once we measured the exact volume of the water, we added the nail and then measured the volume again. To get the volume of the nail, we subtract the initial volume of the water from the volume of the water with the nail. Once we have the mass and volume we again use the formula to calculate the density.

Finally, we measured the density of a liquid. We first measured the mass of an empty 100 mL graduated cylinder. Once we got that measurement, we filled the cylinder about one third full. We then measure the mass of the cylinder plus the liquid and then subtract the cylinder's measurement to get the mass of the liquid. We then get the volume of the liquid simply by measuring it in the graduated cylinder. Once we have the mass and volume, we calculate the density one final time by using the formula .

Our homework for tonight, is to complete pg. 9 which Mr. Paek gave out at the beginning of class to go in our notebooks. This is simply just more examples of finding the different components of the density formula ().

Friday 9.3.10

Today we started the first few minutes of class making sure that everyone was able to access their blogger and google apps account (and as it turns out, mine works). We then proceeded to review the rules of significant numbers. The significant figure rules state that all non zero numbers are significant, zeroes between significant numbers are significant, any zero after a decimal is important, and that any zero used as a placeholder is not significant. After the short review we learned the rules to add, subtract, multiply, and divide using significant numbers. The rule for adding and subracting is that you round your answer to the same number of digits past the decimal point as the smallest number of digits past the decimal point. For multiplication and division, you round to the smallest amount of significant numbers. Finally we learned about scientific notation. When writing a number in scientific notation, you move the decimal until it is directly behind the first significant number and multiply it by 10 to the according power (for example 67,989,097 would be 6.7989097 times 10 to the seventh power). Unfortunatly however we were unable to get to a deminstration that involved fire.

Wednesday 9.1.10

Today during the first 30 minutes of class we finished our measurement lab by measuring five objects three of which had to be a jumbo paper clip, a piece of paper (the long way), and your height. The other two were students choice. We measured these in centimeters. The next step of the lab was to weigh the objects. This had to be done in grams. You had to weigh a jumbo paper clip, a piece of paper, and two objects of your choice. The final step of the lab was to measure the temperature. You had to find the room temperature, and then you had to do two different measures by filling up a beaker of water and finding its temperature.

          For the next 20 minutes of class we learned about the significant figure rule. The significant figure rule has four parts. 1. Digits other than zero are always significant. 2. Zeros between non-zero digits are always significant. 3. Any final zero after a decimal point is significant. Zeros used solely for spacing the decimal point (place holders) are not significant. We then filled out a little piece of paper based on how many significant figures were in each of the measurements. 

          On Friday we will be having a quiz on measurements. There was not any homework for tonight.

Tuesday 8.31.10

Today in class we took a few minutes to label all the important things in the room like the fire exits and water showers. Then we identified some materials. We identified a beaker, flask, Bunsen burner, a ring stand and a funnel.  We also talked about different types of measurements. To start off we got a ruler with a filled in a line on top. We had to estimate the length to the closest we can. With that you only have one guess. That means when you find your measurement it is not exact so you estimate to a reasonable length. When trying to find the measurement of a graduated cylinder, you measure from the lower dip in the water. Then we split into lab groups and started working on measurements. We took measurements in different ways. We found the smallest reading device for each utensil. The most accurate was a 10 ml graduated cylinder. It has the smallest reading device so it is most accurate. Some reading devices were 25 ml for a 400 ml beaker, 10 ml for 100ml beaker. 1 ml for 100 graduated cylinder and .2 ml for 10 ml graduated cylinder, which is the most accurate. After that we take a buret clamp and place a 250 ml beaker under it so it will catch the liquid. Fill the buret with water then open the valve and see how much water drains. The unique this about a buret is that the measurement starts at 100 then drops to 0. The reason for this is so you can see how much water or liquid you dropped or took out. We then recorded how much water was emptied out to the nearest 10nth. Then you let the water drain for 3 seconds and you record how much water drained. That is when we started cleaning up. This lab will be continued…

Monday, 8.30.10

                Today in class we did an alka-seltzer lab. We had to come up with the problem (what we needed to find out), a hypothesis (an “if..then..” statement predicting what we thought would happen), the independent, dependent, and control variables for the experiment, and a step by step procedure. After we found that, we could begin the actual testing.

                Our group tested for how quickly the film canister exploded when different amounts of water were placed inside. We also crushed up our alka-seltzer to create more surface area which would make the canister explode more quickly.

Problem: Finding out how quickly a film canister explodes when ½ of a crushed alka seltzer is added to different amounts of water.

Hypothesis: If we put less water in or crush up the alka-seltzer, the film canister will explode more quickly.

Independent Variable: Amount of water in the canister

Dependent Variable: Speed of the explosion

Control Variables: Canister size and the amount of crushed alka-seltzer

Procedure:

1)      Fill the container with water

2)      Put in ½ of a crushed alka-seltzer tablet

3)      Close cap

4)      Flip canister upside down

5)      Time how long it takes to explode

Data:

1)      ¼ filled with water + ½ of a crushed alka-seltzer – 6:50

2)      ½ filled with water + ½ of a crushed alka-seltzer – 13:14

3)      ¾ filled with water + ½ of a crushed alka-seltzer – 16:30

4)      Fully filled with water + ½ of a crushed alka-seltzer – 9:67

Conclusion: Besides when the canister is full, the more water there is in the canister, the longer it takes for it to explode.

When the whole class was finished with the lab, we had some extra time at the end of class so Mr. Paek showed us some more cyber bullying videos.

Friday 8.27.10

What we tried to figure out in class today was, how long it would take an alka-seltzer rocket to react as quickly as possible while placed in a certain amount of water.

MATERIALS

* 1 or 2 Alka-Seltzer
* 1 Film Canister
* Water supply
* Safety Goggles
* Stop Watch or Clock

First, we filled in our film canister with cold water about a quarter way, then we placed in two alka seltzer in the canister. After that, we closed the film canister and timed to see how long it took for the alka seltzer to react. On our first attempt, it only took about 10 seconds to react. Next, we retried the first step but this time we filled it in about half way. This attempt took about 15 seconds for the alka seltzer to react. On our third attempt, we filled up the film canister with about 75 percent of water in it, this only took about 7 seconds. We then later tried to flip the canister so that the top would be resting on the bottom. With the water only 75 percent of the way filled, this only took about 13 seconds to react.

Independent Variables

* amount of water in the film canister
* either 1 or 2 alka-seltzers in the canister
* cold or hot water added in the canister

Dependent Variables

* how long it took for the the film canister's cap to pop

Controlled Variables

* Temperature of the water
* amount of alka seltzer's in the canister
* how much water was put in
* flipped or not

It might be different for other groups, but the amount of water that made the fastest rocket was when the water was 75 percent full.

http://www.stevespanglerscience.com/img/cache/bcb9b8db117ee64376aedaf7af3595ca/03-06-06-alkaseltzer_rocket-08.jpg
http://www.chem.fsu.edu/chemlab/chm1050lmanual/masspercent/alkaseltzer.jpg
http://i.ehow.com/images/a04/qp/a8/build-alkaseltzer-popper-200X200.jpg