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Wednesday, March 23, 2011

Yeast Pressure Investigation

Today we investigated yeast activity and air pressure in Yeast Beasts in Action. We wanted to know how yeast activity varied in acidic, neutral, and basic mixtures. In order to perform the investigation you need 1 teaspoon of yeast, 50mL of water, 2 beakers, 1 gas sensor, black rubber stopper, 3 test tubes, 1 test tube rack, soda, milk, antacids, Vernier software, laptop, LabQuest Mini, graduated cylinder, 3% hydrogen peroxide, and an eye dropper.

First we set up the Vernier software and connected all the sensors with the LabQuest Mini. Then we placed the three test tubes on the rack and labeled them A, N, and B. Then we measured out 3mL of hydrogen peroxide and poured it into each tube. Then we made our yeast solution by filling up one of the beakers with 50mL of water and 1 teaspoon of yeast and stirring. We used the eye dropper to add 2 drops of the yeast solution to Test Tube A. Then we added 3mL of the soda and put the rubber stopper on top. We then collected the data and recorded the highest pressure of Test Tube A. We waited after the 2 minute mark until the pressure started going down so that we could get a more accurate pressure amount. We repeated these steps for the next two tests, but we used milk and antacids for the mixtures.

My hypothesis was: If yeast breaks down and releases the gas of compounds, then the acidic mixture will have the highest pressure because the other two mixtures will have lower kPa.
The reason I thought that the neutral and basic would have low pressure was because the neutral mixture (milk) would be cold which (as concluded from a previous lab) causes a lower pressure and the antacids neutralize acidity, so I did not think that they would cause a high pressure.

My hypothesis was close, but was not exactly supported by the data. The chart below shows the results of the tests:


Basically, the Basic mixture ended up having the highest pressure at 128.3 kPa. The Acidic mixture was close with 122.13 kPa. Last was the Neutral mixture with 117.19 kPa.
Below are charts containing the pressure info for each mixture:
(The Acidic Mixture)
(The Basic Mixture)
(The Neutral Mixture)

Thursday, March 17, 2011

Law of Conservation of Mass Investigation

Today we investigated mass and weight in the Conservation of Mass Investigation. In order to complete the lab investigation we needed 1-2 packets of pop rocks, 2 balloons, 2 twenty ounce soda bottles (one empty, one full), 1 tsp. of baking soda, 50mL of vinegar, a funnel, graduated cylinder, and a plastic spoon. There were two tests to complete, the Pop Rocks test and the Baking Soda/Vinegar test. Our problem was: What will happen to the balloon when the Pop Rocks are dropped into the bottle? Our hypothesis was: If we put the balloon on the bottle and drop the Pop Rocks, then the balloon will inflate because of the carbon dioxide in the Pop Rocks that will be released.



We began with the Pop Rocks test by pouring out half a packet of Pop Rocks into one of the balloons. First we had to stretch the balloon to make it more flexible. Then once the balloon was filled we attached the balloon to the soda bottle, but we did it in a way so that the balloon was at the side of the bottle and we could control went to drop in the Pop Rocks. Like this:



Then we poured it into the bottle, and watched. Basically what happened was the balloon stuck upright, and the part of the balloon covering the opening in the bottle filled up slightly. The Pop Rocks fizzed and dissolved in the soda. When we looked around, compared to other groups' balloons, ours had not been filled up much at all. It may have been because we were only able to use half the packet of the Pop Rocks, or maybe because we did not stretch our balloon very long. Then we got the idea to shake our bottle from one of the other groups, it maybe released the carbonation from the coke because the balloon started inflating a lot more. Soon there was only two inches of balloon not inflated. It looked somewhat like this, but the balloon was much smaller:



Then we did the baking soda and vinegar test. We went through pretty much the same procedures, except we used the empty bottle and filled it with 50mL of vinegar. Then instead of Pop Rocks, we filled the balloon with baking soda. Then we attached the balloon onto the bottle and poured in the baking soda. The second the baking soda touched the vinegar it started bubbling and fizzing. In less than three seconds the vinegar-baking soda had bubbled up to the top of the bottle and the balloon had fully inflated. But, the reaction soon ended, just as quickly as it happened. The vinegar mixture bubbled back down to the bottom of the bottle, and the balloon deflated slightly.


My hypothesis was supported, because it was pretty much what happened. I did not know all the details of how the balloon would be inflated, but I knew carbon dioxide was inside of the Pop Rocks, and figured it would end up inflating the balloon. Now I know exactly how it worked. When being made, Pop Rocks are boiled at a very high pressure with carbon dioxide, and the end result is tiny bubbles of carbon dioxide compressed at 600 PSI inside the candies. So when they are opened up or dissolved, the carbon dioxide is freed. So when put in the bottle of soda, the Pop Rocks were dissolved and the carbon dioxide went up into the balloon. Something else that I left out in the hypothesis was that the soda also contributed to the inflation of the balloon. But after some research, I found that the Pop Rocks actually released carbon dioxide from the soda. So the soda also helped inflate the balloon.

Something I thought was interesting was that the Pop Rocks and soda test did not show a chemical reaction, but a physical reaction. The reason is being that the soda is just dissolving the Pop Rocks which releases its carbon dioxide, and there is no real reaction.

Tuesday, March 15, 2011

Chemical Reactions and Temperature Investigation

Today we had a Chemical Reaction and Heat Lab Investigation where we investigated how temperature varies chemical reactions. The materials needed for this lab investigation were a 600mL beaker, a stirring rod, metal tongs/clamps, Vernier software, temperature probe, ring stand, graduated cylinder, 3 alka-seltzer tablets, stopwatch, hot plate, ice cubes, laptop, and 665mL of water.

My hypothesis was: If increased temperature increases the reaction rate, then the Hot Test will have the quickest dissolve time because it has the highest temperature. In order to find out if this hypothesis would be supported or not, I had to complete the three tests: Hot, Room Temperature, and Cold. Each test involved filling the beaker up with water, getting it to a certain temperature, and dissolving the tablets in the water. The difference was that the Hot test used a hot plate and needed to go up to 50 degrees Celsius, the Room Temp. test just needed to be regular water, and the Cold test needed ice cubes.

Our results are shown in the chart below:

The proved our hypothesis to be true because the Hot test ended up having the shortest dissolve time (23 seconds). Room Temperature was only 16 seconds behind, and Cold was 97 seconds behind. Basically, hotter temperatures will tend to quicken the rates of chemical reactions (especially when concerning the dissolving of something).

Below are diagrams of how the beaker looked for each test.
This was my diagram for the Room Temperature test. Bubbles were flying from the alka-seltzer tablet (as shown in diagram). In fact, the bubbles were coming so rapidly that the tablet was spinning round and round until it settled back at the top to dissovle into foam.



Then there was the Hot test, immediately after the tablet was dropped into the heated water it started to fizz. All around the tablet was bubbly foam, unlike the Room Temp. test, bubbles did not start spurting out until a little later. It mainly just fizzed.

Last was the Cold test. There were bubbles during the Cold test, but they were rather large and came very slowly. After about a minut the tablet started to really fizz and then it started looking like the Room Temperature beaker.





Friday, March 11, 2011

Chem Think; Chemical Reactions


1. Starting materials in a chemical reaction are called:
1A. Reactants

2. The ending materials in a chemical reaction are called
2A. products

3. The arrow indicates a __________ has taken place.
3A. A chemical change
4. All reactions have one thing in common: there is a ______ of chem. bonds
4A.rearrangement

5. Chemical reactions always involve ______ old bonds, ______ new bonds, or both.
5A. breaking, forming

6. In all reactions we still have all of the _______ at the end that we had at the start.
6A. atoms

7. In every reaction there can never be any __________atoms or ________
7A. missing, new

8. Chemical reactions only _______________________ in the atoms that are already there.
8A. rearrange the bonds

9. Let’s represent a reaction on paper. For example, hydrogen gas (H2) reacts with oxygen gas (O2) to form water (H2O):

H2 + O2 --->H2O

If we use only the atoms shown, we’d have two atoms of H and two atoms of O as reactants. This would make one molecule of H2O, but we’d have one atom of O leftover. However, this reaction only makes H2O.

Remember: reactions are not limited to 1 molecule each of reactants. We can use as many as we need to balance
the chemical equation.
A balanced chemical reaction shows:
a) What atoms are present before (in the reactants) and after (in the products)
b) How many of each reactant and product is present before and after.

10. So to make H2O from oxygen gas and hydrogen gas, the balanced equation would be:

____ H2 + _____O2 ---> _____ H2O

Which is the same as:



11. This idea is called the _____________
11A. Law of Conservation of Masses

12. There must be the same _____________ and the same number of _____________
before the reaction (in the reactants) and after the reaction (in the products).
12A. elements, atoms

13. What is the balanced equation for this reaction? 2Cu + 1O2 → 2CuO

14. In the unbalanced equation there are:
14A.
15. To balance this equation, we have to add ______ molecules to the products, because this reaction doesn’t make lone _____ atoms.
15A. CuO, oxygen

16. When we added a molecule of CuO, now the number of _____ atoms is balanced but the number of ____ atoms don’t match. Now we have to add more _____ atoms to the reactants.
16A. Oxygen, Cu, Cu

17. The balanced equation for this reaction is

2 Cu + 2 O2 ---> 2 CuO

This is the same thing as saying:


18. What is the balanced equation for this reaction? (Use the table to keep track of the atoms on each side.)
1 CH4 + 2 O2 → 2 H2O + 1 CO2


19. What is the balanced equation for this reaction? (Use the table to keep track of the atoms on each side.)
2 N2 + 3 H2 → 2 NH3

20. What is the balanced equation for this reaction? (Use the table to keep track of the atoms on each side.)

2KClO3 → 2 KCl + 3 O2


21. What is the balanced equation for this reaction? (Use the table to keep track of the atoms on each side.)

SU M M A R Y

1. Chemical reactions always involve:
1A. breaking and/or making bonds

2.The Law of Conservation of Mass says that the same atoms must be:
2A. present prior and after the chemical reaction

3. To balance a chemical equation, you change the _____ in front of each substance until there are the same number of each type of __________ in both reactants and products
3A. coefficients, atom

Wednesday, March 9, 2011

Polymer Lab Group Investigation

Polyvinyl Lab Group Investigation: Polyvinyl Acetate and Borax Investigation

After the first polymer lab, my group was inspired to further investigate the properties of borax for our next investigation. We wanted to know if borax was truly responsible for the flexibility and rebound of the polymer. In this investigation, we completed three trials: Trial 1 would be the control (nothing would change), Trial 2 would be our variable (35 mL of borax solution), and Trial 3 would be another variable (15mL of solution). The control is used to compare the other Trials with. Trial 2 will allow us to see if more borax solution will allow more “cross-linking” thus leading to tighter bonds and more flexibility/higher rebound. By completing Trial 3, we can back up our theory of Trial 2, because if our theory is correct, then the polymer in Trial 3 will not have much flexibility or very high rebounds. Our hypothesis was If the polymer is most flexible and achieves the highest rebound tests in Trial 2 (the trial using more borax solution), then the borax is responsible because more borax solution was used in it, thus proving that more borax=more flexibility. If our hypothesis was correct, the results should have shown the polymer in Trial 3 to be less flexible or have not very high rebounds. Also, Trial 2 should have shown to be very flexible and fairly high rebounds (in comparison to Trial 1).

As it turned out, Trial 2 did have the highest average (14 cm) for the rebound tests, Trial 3 had the shortest (5.3), and Trial 1 was right in between (10.3). Trial 3 was incredibly mushy, wet, and sticky. It was so wet and sticky that it did not really bounce at all when dropped, and it was very difficult to drop due to it sticking to our hands. Below is a picture of what the Trial 3 Polymer looked like:

Here is what all three Trials looked like side by side:
Trial 1 was soft and moldable. Trial 2 was very firm, it was also stickier than Trial 1, but not squishier. It was also a lot denser. Trial 3 was watery and loose and shapeless. Something that I noticed was that after the removal of Trial 1 polymer, there was a little bit of water and some glue bits left over in the beaker. After the removal of Trial 2, there was at least 30mL of water in the beaker along with glue bits. After the removal of Trial 3, there was no water left, but there was some glue left. I think this is partially because we may have taken out Trial 2's polymer too early, and we may have taken out Trial 3's polymer too late. Thus the polymer soaked up all the water which may have resulted in it's watery-ness.

Then there were the flexibility tests. Below is the chart containing information for all of the tests.

To sum up all the information, at 54 cm, Trial 3 had the most flexibility, at 37 cm, Trial 1 had the second most, and at 26 cm, Trial 2 had the least. There are many explanations for this, but I think that perhaps our information is not completely correct. For one thing, different group members stretched the polymers, which would mean some of them may have been stretched harder and faster or slower. This could speed up the breaking of the polymer, or slow it down. Another thing is that with Trial 3, as mentioned previously, it had been left in the beaker the longest, resulting in it sucking up all the water and being very flexible. Although, Trial 2 was definitely not very flexible, despite the variables. It snapped easily, and was not all that flexible.

In conclusion, our hypothesis was partially correct because Trial 2's results did show that more borax provides more rebound, but it does not necessarily provide more flexibility.





Thursday, March 3, 2011

Sodium Silicate Polymer Lab Investigation




How do you make a sodium silicate polymer? That is the question we answered in our latest lab investigation. This is my hypothesis (what I thought was going to happen): If you mix ethyl alcohol with a sodium silicate solution, then you will make a polymer because when sodium silicate is added to ethyl alcohol, silicate chains form and the oxygen atoms of the silicate are replaced by ethyl. In order to find out if this hypothesis was supported, we mixed 12mL of sodium silicate with 3mL of ethyl alcohol. A polymer was formed, thus proving our hypothesis to be correct. We then rolled up the polymer into a ball, and went through some rebound tests. Then we froze the polymer ball, and went through the rebound tests once again. Below is a graph showing our results:



As with our first lab, once the polymer was frozen, it bounced slightly lower. When we compared our results with the group behind us, we discovered that our ball bounced slightly higher, and was smaller in diameter. Our ball turned out pretty good, but not very easily. At first we thought we might even have to start over because the polymer would not form. We had to put it under a lot of water because it got squished when we were rolling it. The polymer was squishy and moldable, but only if you touched it. Otherwise it stayed firm and held it's shape. It was sort of white, and also see through. It looked very similar to an ice cube or frozen water.

Sort of like this: After we froze the ball it became almost completely white and opaque.

We had originally done a lab about polymers that involved borax and glue, where we also made a polymer. Below is a diagram that I created to compare and contrast the two polymers:
Carbon is the basis of much life on Earth, the next best thing, as many believe, would be silicon. Silicon has an equal number of electrons in it's outer shell as carbon. This means that silicon can also create four bonds just like carbon. Certain types of carbon molecules (like carbon dioxide) derive from silcon.

Silicone polymer is a synthetic polymer created with silicon. It is a plastic polymer as well. It is similar to plastics, since it is a plastics polymer.

I know that a chemical reaction has taken place between two mixed liquids when they change their state of matter. For example, when borax solution is mixed with glue solution, a chemical reaction occurs and the mixture becomes solid instead of liquid. Same with ethyl alchol and sodium silcate.

I could find out what liquid was pressed out of the mass of a crumbled solid as I formed the ball by looking at it, and studying it. Also by smelling it, and if I knew what had been used to create the ball, I could probably make a hypothesis as to what it was.

When I compared my group's polymer ball with another group's, I discovered that the other group's "super ball" was a lot larger in diameter, and it also bounced a lot lower. After the other group's ball was frozen, it's highest bounce was 10cm, and ours was 14cm.