Yeast Beast in Action Investigation

Our first test of the gas pressure was on our acid, the 3 mm of Diet Coke and hydrogen peroxide. Once we added the hydrogen peroxide to the soda all carbonation dissipated. When the yeast was added, the fizzing began again, but not before subsiding into an extremely thin layer of foam at the top of the liquid. We added the rubber stopper to begin testing the pressure. After two minutes with the yeast reaction taking place, the pressure had risen from 96.88 kPa to 104.7 kPa.

In the milk/hydrogen peroxide (neutral) test, there was also a bubbly, foaming reaction when the yeast was added. This time the foam was taller than in the soda test. Our neutral test boasted significantly slower and lower reactions than in the acid. In two minutes the pressure increased from 96.88 kPa to only 99.77 kPa.

For our final test of antacid and hydrogen peroxide (base), another foam layer was created on top. This one was the largest of the three tests. With the yeast added, the pressure increased from 96.88 kPa to 101.79 kPa, the second highest recording in our experiment.

Here are our results:


My group's hypothesis was that the acidic mixture would produce the greatest pressure, followed by the neutral mixture and the basic mixture.

The greatest yeast activity was in the acid, judging by its production of the most gas pressure. This may be due to several reasons, such as the corrosive nature of the acids broke down the yeast or hydrogen peroxide faster. Also, the diet coke we used contained gases to begin with, so CO2 was being released along with oxygen from the hydrogen peroxide. This addition may have added to the results.

The lowest yeast activity was found in the neutral mixture. This may have been simply because the substance was neutral and didn't really have any effect.

Some sections of our hypothesis were supported by this experiment. We predicted that the acid would have the greatest effect on the yeast because of its corrosive properties. We mixed up the neutral and basic mixtures however, saying that the base would cause less of a reaction than the neutral compound. When we actually tested the experiment, this was switched, because the neutral mix remained, well, neutral and didn't have much affect at all. The hydrogen peroxide was used in all of the mixtures in this experiment because of it chemical reaction to yeast. Without the hydrogen peroxide there may not have been much increase in pressure, due to lack of gas release. Another interesting aspect of this experiment was the fact that our starting pressure was a consistent 96.88 for all of the tests. The beginning kPa is often varied in these tests. From this experiment, we learned how different PH levels can affect the gas pressure in an enclosed area.

Conservation of Mass Investigation

My group hypothesized that the reactions with soda and pop rocks would produce enough gas to partially inflate the balloon, and the test with baking soda and vinegar would inflate the balloon to a greater degree,

When we added the pop rocks to the soda, there was an immediate fizzing that took place. At first the soda itself just produced bubbles, but then the ballon began to inflate from the gases being released. The balloon continued to slowly inflate for about 30 more seconds, until it was about the size of a baseball. When the gas release ceased, the pop rocks could be seen floating on the surface.

In the experiment with baking soda and vinegar, the reaction began instantly and was much faster than the previous test. The reaction was larger despite having significantly less liquid than before. This time the balloon swelled up to about the size of a very large grapefruit in a short amount of time. The ballon felt more solid in this experiment too, which also shows it inflated more this time. After we poured the vinegar back into the graduated cylinder for analysis, there seemed to be more liquid than we started with, but the vinegar had bubbles interspersed throughout, which would have offset the measurement.

Our hypothesis was partially supported. Both balloons inflated to a greater degree than we had predicted they would. We did predict that the baking soda and vinegar would have a more powerful reaction. We thought this from past experience making volcanoes and from the fact that the two ingredients are more commonly used in experiments like this by teachers. If baking soda and vinegar made a lesser reaction than pop rocks and soda, then they wouldn't be used. For the pop rocks experiment, some factors that may have affected the differing results among groups were the flavors and colors used in the rocks as well as the type and level of carbonation of the soda. It was determined that the experiment conducted was not a chemical reaction but a physical one, because the CO2 in the candy and soda was simply being released and no bonds were broken or created. The soda was used as a reactant because of its Carbon Dioxide content, as were the pop rocks. In the baking soda and vinegar experiment, a combination of CO2 and water vapor was released.

Chemical Reactions and Temperature Investigation

My group's hypothesis was that due to greater energy in the heated water, the alka-seltzer would dissolve at a quicker rate, followed by the room temperature water and finally the chilled water.

For our test of the hot water, the initial room temperature was 24.5 degrees C. We set up the beaker and plugged in the hot plate. The tempe rature in the water immediately started to climb. After a few minutes, the water temperature had gotten to 55 degrees C, but we had forgotten to grab our tongs, so we took the water off the burner and let it return to 50 C. As soon as we dropped the alka-seltzer tablet into the hot water it began to fizz and dissolve. The tab floated on the surface, probably suspended by vapor releasing from the water. The tablet had completely disappeared 22.46 seconds into the experiment. After the alka-seltzer dissolved, the temperature in the water was 48.9 degrees C.



For the room temperature test, we didn't need to do anything more than measure the initial temperature of the water prior to the reaction. It measured 25.3 degrees C. Once the alka-seltzer was added, the temperature actually started to decrease, dropping to 24.9 degrees by the end of the experiment. The tablet visibly took longer to dissolve than in the heated reaction. In addition, the tablet sank directly to the bottom of the beaker in this experiment. In the end, it took 36.4 seconds for the alka-seltzer to dissipate.



In the final test, we added ice cubes to half the mount of water we had used in our previous two tests. We stirred well, until the ice had melted slightly into the water. Our thermometer measured the water temperature at 1 degree C before we added the tablet. Once the alka-seltzer had been introduced, a pattern became clear among the experiments. This reaction was by far the slowest of all. Like the room temperature test, the tablet sank to the bottom of the beaker. The alka-seltzer didn't fully dissolve until 2 minutes and 8 seconds after the start of the test. The tablet raised the water's temperature to 1.3 degrees C. The pattern shown by the three experiments was that the warmer the solvent, the faster the reaction. This is because there is more energy in hot materials, and more energy makes things happen more quickly.



Our hypothesis was supported. The hottest water dissolved the water the fastest, because it had more energy than any of the other test samples. Only the heated water made the tablet float, because it as creating more vapor that rose to the surface and carried the alka-seltzer with it. Two errors that may have occurred would have been in our heated test. Fist, we overheated our beaker at first, so we had to wait for he temperature to come back down to 50 degrees C. Also, we didn't follow the directions correctly and took out our thermometer before the experiment occurred. This may have lead to an inaccurate measurement for the ending temperature of that test. We corrected this mistake through the rest of the testing session.

ChemThink Reactions Tutorial Questions.

1. reactants
2. products
3. chemical reaction
4. rearrangement
5. breaking, forming
6. atoms
7. missing or new
8. rearrange the bonds
9a. 2
9b. 2
9c. 1
9d. 1
10a. 2
10b. 1
10c. 2

#of Elements in reactants Elements #of atom products
4 H 4
2 O 2

11. Law of conservation of mass
12. mass, atoms
13a. 2
13b. 1
13c. 2
14a. (Cu reactant) 1
14b. (O reactant) 2
14c. (Cu product) 1
14d. (O product) 1

15. CuO, O
16. O, Cu
17. 2, 1, 2

Reactants Products
Cu-2 Cu-2
O-2 O-2

18. CH4- 1
O2-2
H2O- 2
CO2- 1

19. N2- 1
H2- 3
NH3- 2

20. KCIO3-2
KCI-2
O2-3

21. AI-4
O2-3
AI2O3-2

Summary

1. breaking bonds, making bonds, or both
2. present before and after the reaction
3. coefficients, atom

Polymer Lab Group Investigation

Our experiment began by learning that we couldn't do our experiment. With some quick thinking, we decided that we would just redo our experiment with the glue polymer, except we would alter the amount of borax used in each test.

Our first test found my table doing exactly the same steps as the lab last Tuesday, except we used half the borax in our solution. Once we began stirring, it was clear that the loss of borax had definitely caused differences in the polymer. There was a lot of extra water at the bottom of the beaker that the glue wasn't absorbing. The polymer seemed especially gloopy and thin, probably because there wasn't enough borax to bond all of the water and glue together. Once we took the polymer out of the beaker, we noticed that it was stickier than the original polymer. This may have been because the borax wasn't there to make the polymer more of a gel-like consistency rather than a glue-like one. The polymer was also more malleable than the first one, due to the lack of borax for solidification. When we tested the rebound of a quarter-sized chunk of the polymer, we got an average bounce of 7 cm. This was lower than the average of the normal glue polymer. The lower score may have been explained by a less together substance, that would make retaining a ball-like shape difficult. After the rebound test was done, we poured 25 mL of borax water onto our polymer and it hardened to the point where it was essentially the original polymer in its properties.

For our second test, we did just as we had in the first test and last week's lab, but we used 4 teaspoons of borax in the mixture. When we mixed the glue and borax water, it started to bond together very quickly. This polymer was probably the strangest we had created up to this point. As we inspected it, we noticed that on the outside, there was basically a coat of watered down glue that ran off on our hands. The center of the polymer, however, was very solid and hard. The reason for this drastic contrast must have ha something to do with the excessive borax that we used, whether that means that it caused a hardening in only a small amount of the polymer or that it kept the glue on the outside in a liquid state. Once a lot of the liquid glue had run off, we tested the rebound of our polymer. It scored an average of 12 cm, the highest of any of the glue-based polymers. This may have been because the extra borax concentrated the glue so that it could bounce higher.

My hypothesis about the rebound of the polymer with reduced borax was supported. There was a lower rebound because the polymer was not as solid as the original one we created. My hypothesis about the polymer with added borax was not supported, because i thought the borax would make the polymer more dense and it wouldn't bounce as high. However, it had the highest average bounce of any of the glue-based polymers. An error that may have occurred may have been in the measurement of our glue, as we had to judge the 40 mL by eye. However, we approximated as best we could, so I don't think there was much of an issue. This experiment was a success in finding out the effects of adding or subtracting borax from the glue-based polymer solution.

Sodium Silicate Polymer Lab Investigation Response

Observations, Results, and Conclusions

In its liquid form, the sodium silicate was a clear, syrupy substance. The ethyl alcohol smelled extremely strong. When we mixed the water glass with the ethyl, a reaction took place immediately. The substances began to solidify and clump together on the stirrer, leaving some liquid and chunks of polymer at the bottom. The polymer was white and extremely brittle and crumbly. The ball seemed to be more compact than our polymer on Tuesday. The surface of the polymer was wet, and it was difficult to mold into a ball.

Comparing and contrasting the two polymers we created, it's easy to see distinctions in the two. The first polymer was much more like a gel, and extremely malleable and soft. The polymer we created today almost had the consistency of wet sugar, and was difficult to mold and split. It was a slightly darker shade than that of Tuesday's polymer, and it bounced an average of more than 10 cm higher as well. However, there were some definite similarities between the two. They both took on a whitened color, and both had bouncy properties. Chemically, the same process occurred when the solutions combined, causing the monomers to bond together and become more solid.

Carbon and Silicone are both able to make polymer bonds because they have similar chemical structures. They are both solids in the non-metal family, meaning they have very similar structures. Because Plastics are made of carbon-based polymers, and silicone is a similar element, then silicone polymers would be similar to carbon polymers.

It was easy to see that a chemical reaction had taken place when the two liquids mixed because they began to mend together and change their phase of matter. The liquid that came out of the crumpled mess would probably have been the ethyl, because it smelled like alcohol and didn't damage our hands when we handled it.

We measured our ball against Table 7's ball. There's was larger, lumpier, and less translucent than ours. It also had an average 20 cm rebound for both tests, as opposed to our average rebounds of 19 cm for the heated test and 17 cm for the cooled test.

My hypothesis was supported in all facets of the experiment, except for the initial coloration of our silicone polymer. Because both of the liquids were clear, I predicted a clear polymer, as opposed to the off-white that our polymer actually was. One thing I thought was interesting in this experiment was the different rebound of the silicone ball as compared to the quarters of the glue-based ball. The averages were higher in the silicone ball probably because the silicone seemed more compact and hard, while the glue quarter was soft and loose.

Overall, this experiment and the experiment on Tuesday well demonstrate what can be done with polymers in an interactive way.

The Science of Addiction

Neurons are the signals that make up the nervous system. They are responsible for transmitting the body's messages. Neurons communicate with each other in the synaptic gap between the axon endings and dendrites of the next neurons.

In the brain, there is a section called the reward pathway that is responsible for controlling our senses of motivation, reward, and behavior. The reward pathway makes us feel good when we eat, drink, and have sex. It is connected to other parts of the brain, allowing it to have a perception of what you are doing. Dopamine is released to make the body feel pleasure. The pleasure reenforces the action in your memory, making you want to perform it again.

Drugs release dopamine into the brain when ingested, causing the sensation of a "high." In the brains of drug addicts, the dopamine receptors have been damaged, as the brain adapts and disposes of dopamine receptors in the synapse. The absence of receptors will cause an addiction in the drug user, because the use of doping substances is the only way they can feel the dopamine again. The more quickly a drug enters the system, the more likely you are to become addicted to it. Once the brain has begun to adapt to the drug, the brain can become deficient in judgement, learning, and memory. The continued use of the drug also becomes hard-wirde into the synapses. Too great of an ingestion can cause a lethal overdose, and use over a long period of time can have severe effects on the mental function of the abuser.