Acid and Base Yeast Lab

When going into this experiment, I believed that out of the three types of pH levels, acid, base, and neutral, that a neutral pH would allow yeast to thrive the most, considering the phrase "everything in moderation" and how nature likes a balance. My hypothesis never received a truly proper testing, due to two false starts. First, I made a mistake in accidentally pouring in 3 mL of the yeast solution, instead of 2 drops. This caused the air pressure to boil to a point of popping off the gas cap (in black) explosively!

After this popping, we attempted to forcibly keep it on, which caused the air pressure to rise to 157 kPa! If it reached northwards of 200 kPa, I believe the Pyrex would have shattered, causing facial lacerations and other maladies. Next, we restarted the whole experiment, realizing that the potential for shattering probably wasn't wanted when doing this lab. However, this time, we were confronted by the fact the the Vernier interface automatically ends the testing, and we had been waiting about 20 seconds to set a baseline, interfering with our true results. We figured this out right after finishing our acid test. We went through the test for the other two, and the neutral achieved 105.2 kPa at two minutes, while the base achieved 101.5 kPa.

The test tubes during the second test

Finally, we retested the acid one final time. It ended up at 101.1 kPa.

The diagram of the test tubes and their heights

In hindsight, seeing how other groups' results supported that acids where the beast, I failed to take in the chemical processes associated, and how acids are more likely to support the advent of more singular oxygen and hydrogen atoms, which causes air pressure. Currently, I have no idea which one was the "right" one, and which was more helpful to yeast. Personally, I believe that the acid caused more pressure.

I believe this lab has actual industrial uses, in the sphere of testing the amount of CO2 that can be injected into to soda. The scientists would continually inject CO2, and when the container popped, they could set a baseline for the amount of pressure it could withstand. If the soda makers needed more CO2, then they could create a stronger bottle.

Conversion of Mass Investigation

When beginning the pop rocks/soda part of the lab, I believed that the reaction between the two would cause a effervescent release of carbon dioxide.


As you can see, that prediction was correct. A physical reaction occured, melting away the sugary coating off Pop Rocks, which reached the C02 in it, and it manifested itself as bubbles. These bubbles rose into the balloon, expanding it to this position:
However, I think the reaction could have been amplified if we used a less flat bottle, because then we would have more carbon dioxide. Also, I wonder if different flavors would magnify the amount of carbon dioxide released. Maybe a more acidic soda would cause some corrosive powers, getting to more of the CO2 pockets in pop rocks.

Next, we began the baking soda/vinegar half of the experiment.
Going in to this experiment, I predicted that the baking soda and vinegar together would create a bubbly reaction that would cause the balloon to inflate.

I feel my hypothesis was supported because of the large balloon inflation. Also, I believed that the baking soda and vinegar would create a larger balloon than the previous experiment, because of how simplistic and concentrated the baking soda and vinegar were, compared to having all the additives in soda and pop rocks.

(deep introspection)

Finally, all three of my hypothesis were correct. We also poured all of the vinegar back a beaker, and it had the same amount of vinegar in it! For this reason, I think this was an interesting lab to introduce the Law of Conversion of Mass. However, I wanted to weigh them at the start and the end to make sure they were the same weights. Also, I would like to see if I could somehow cause the carbon dioxide to release back into the soda, and see if it had a similar amount of fizz.

Chemical Reaction & Heat Lab

Right before writing my hypothesis, I realized how heated materials released more energy. This extra energy I believed would add to water's solubility of alka seltzer. Therefore, my hypothesis was that the hotter the water, the quicker the alka seltzer would dissolve, because of the higher amounts of energy.

I feel that the experiment fully supported my hypothesis, showing that the hotter the water, the quicker the reaction will occur. The alka seltzer, at 50 degrees C dissolved in 23 seconds. The alka seltzer at 24 degrees C dissolved in 39 seconds. Finally, the alka seltzer at 3 degrees C dissolved in 116 seconds, or 1:56.

Graph detailing the curve associated with temperature (x-axis) and time to dissolve (y-axis) corrrelation

I created this equation in three steps. First of all, I realized that the scatter plot of the points could assume the position of an exponential, quadratic, or logarithmic equation. Second, I used the x-axis as the temperature of the water before the alka seltzer was dissolved, and the y-axis as the time, in seconds, that it took to dissolve. Finally, I used a handy application on my TI-84 Silver Plus calculator that would accept these points and use them to create an equation. After fiddling with different types of equations, I realized the exponential model was the most effective. The equation is that y=119*(.96^x). Tomorrow in class, I would like to choose a random point on this axis and check my model's accuracy.

The hot beaker's high amounts of alka seltzer being released
The room temperature beaker's average amount of activity

The cold beaker's little activity

Along with the expected addition of the extra energy from the heated water, the alka seltzer, in the hot beaker, constantly shifted positions and was very jittery. Then, the other two alka seltzer's acted expectantly less jittery and full of energy.

I wonder if the makers of alka seltzer have investigated in adverse affects when taking alka seltzer while having a very high fever, like 105 degrees F. I think that this would happen due to the extremely quick release of these bubbles, which might agitate the stomach.

ChemThinks; Chemical Reactions

1. Starting materials in a chemical reaction are called reactants.

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

3. The arrow indicates a chemical reaction has taken place.

4. All reactions have one thing in common: there is a rearrangement of chemical bonds.

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

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

7. In every reaction there can never be any missing atoms or new atoms.

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

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 2 atoms of H and 2 atoms of O as reactants. This would make 1 molecule of H2O, but we’d have 1 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:
4 H2 + 2 O2 -> 2 H2O
Which is the same as:

11. This idea is called the Law of Conservation of Mass.

12. There must be the same mass and the same number of atoms before the reaction (in the reactants) and after the reaction (in the products).

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

14. In the unbalanced equation there are:

Reactants: 1 Cu atoms, 2 O atoms

Products: 1 Cu atoms, 1 O atoms

15. To balance this equation, we have to add 2 copper molecules to the products, because this reaction doesn’t make lone oxygen atoms.

16. When we added a molecule of CuO, now the number of oxygen atoms is balanced but the number of copper atoms don’t match. Now we have to add more copper atoms to the reactants.

17. The balanced equation for this reaction is

2 Cu + 2 O2 -> 2 CuO
This is the same thing as saying:
Reactants Products

# Cu atoms is 2 = #Cu atoms is 2

# O atoms is 2 = # O atoms is 2

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.) 1 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.) 2 KClO3  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.) 4 Al + 3 O2  2 Al2O3

SUMMARY


1) Chemical reactions always involve

2) The Law of Conservation of Mass says that the same atoms must be

3)To balance a chemical equation, you change the number in front of each substance until there are the same number of each type of atoms in both reactants and products.

Polymer Lab Group Investigation

Before beginning our lab, I felt that the corrosiveness of the acetone and ethanol would be much more effective at breaking down the polymer. However, the story was far to the contrary. I believe my hypothesis was not supported by the findings of our lab.

(change in size of the polymer)

The lemon juice, with its pH of 2.7, quickly dissolved the polymer's links, while the acetone and ethanol did very little. Lemon juice's acidity seemed to quickly and effectively unhook the polymer. You could even see small little polymers, of a few monomers that remained together. As a consequence, the whole beaker fogged up. However, I think that the acetone and ethanol would have more gradually dissolved the bonds, due to any corrosive's prolonged weathering process. The immediate effects of the acetone and ethanol were small due to their neutral pH. When the polymer broke down, it had a very slimy and floppy texture. When compared to the stagnant control test, the lemon juice-dissolved polymer was roughly 90% smaller in mass.

The polymer before depolymerization

The depolymerized product

The acetone weathered polymerThe milky lemon juice beaker

During our experiment, we changed what we were going to do. Instead of making a double batch of borax and water, we realized that we could just use the 25 mL of borax and water twice out of the same glass. Also, we thought that stirring the polymer with the desired corrosive would excite depolymerization. However, there was no change due to the stirring.

I believe that our choice of acetone and ethanol were redundant, due to the similar properties in corrosion. Instead, I would like to test an extreme base, like bleach, which has a pH of 14. I am very surprised though that acetone didn't quickly dissolve the polymer into monomers, especially because of the big label that says "Do not use near plastics." Also, it is used as nail polish remover because of its ability to corrode substances, like nail polish.

Overall, I feel our experiment was successful in the manner that it gave extremely conclusive results, finely showing that lemon juice was the most effective way to break a polymer into monomers.

Sodium Silicate Polymer Lab Investigation

When I first saw the sodium silicate being poured, I immediately thought that the polymer (in all of its snowball-esque glory) created was going to be much thicker than our last carbon based experiment. Not only would this cause a harder ball, but also a denser one. Besides this correct hypothesis, I did not fully realize the waxiness and crumble that would be associated with our second polymer. I believe that the heightened density allowed for it to bounce 7 cm higher than our last polymer.

However, when measuring the ethanol and sodium silicate, I forgot to wash them off, leaving a bit of chalky polymer on the bottom of the graduated cylinder.

Once both the ethanol and the sodium silicate met, a film developed where the ethanol had reached. This surreal effect illustrated the nearly instant creation of a polymer, compared to the last polymer. The new polymer formed extremely quickly. However, it was very hard to get all of it out of the beaker, and it left a waxy residue behind. Even when molding the ball, the polymer was very crumbly and tough to mold into a ball.

When dropped, our ball had a rebound of 2/3, while our last experiment was closer to a 2/5. When frozen, both times it was slightly less bouncy. I attribute this decrease to our great shaping beforehand, which decreased any effectiveness in the drop in temperature because then optimization of density was little and negligible.

Next time I would like to use another chemical to see if they could replicate ethanol's water removing process, and then use a separate chemical to be the cross-linker. Also, I was wondering if you could create a bipolymer, which would have the inside of a silicon based polymer, but with a carbon-based coating that could protect the inner layer from brakeage.

The Science of Addiction

Natural Pathways in the Brain

In the brain, networks of neurons form, each with an axon, dendrites, soma, myelin sheath, nodes of ranvier, synaptic cleft, and an axon hillock. They send chemical and electrical signals to control sensory feelings and motor functions. For example, the reward pathway uses signals from sensory neurons so you are rewarded for advantageous behavior like eating, drinking, and reproduction. It creates this feeling so you are more likely to complete this action again.

These neurons communicate through the synapse. The small area between the sending neuron and the receiving neuron is known as the synaptic cleft. At the end of the sending neuron are vesicles, small packets that hold together neurotransmitters. In the reward pathway, the neurotransmitter of choice is dopamine. Once an axon reaches its action potential, it lets in Ca++ ions, which triggers the vesicles to release. They spill into the synaptic gap, and make their way into the dopamine receptors at the end of the receiving neuron. The dopamine receptors trigger a second messenger to be created, which then triggers a nerve impulse that releases any neurotransmitter of the axon of the receiving cell. The receiving cell then becomes the sending cell and the process repeats.

However, glial cells also function to assist the neurons. There are three main types of glial cells: oligodendrocytes, microglia, and astrocytes. Oligodendrocytes form the myelin sheath, speeding up chemical impulses during action potential while protecting the axon, too. They are made of lipids, or fats. Microglia defend the neurons, chomping up any invading bacteria. Astrocytes are the arguably the most important and mysterious of all glia, that keep the structural integrity of the neuron, while feeding it nutrients and eating any unneeded neurons. Also, they regulate blood flow with "end feet" on blood vessels. But above all, they can create and modify transmission. These are known as "gliotransmitters". Scientists are confused on the process, but the astrocytes are extremely involved with Alzheimer's, ALS, and AIDS.

Drugs Alter the Brain's Reward Pathway

How drugs work

All drugs either inhibit or excite the release of neurotransmitters and their associated processes. These include alcohol, anabolic steroids, cocaine, dissociative drugs, GHB, Rohypnol, hallucinogens, heroin, inhalants, marijuana, MDMA, methamphetamine, and nicotine. Drugs emphatically change the way the brain works quickly. For example, methamphetamine triggers the quick release of dopamine into the synapse throughout the reward system, causing addiction due to the reward of having something that chemically makes you happy. Also, the quicker the drug causes a high, the more addictive it is.

What drugs do to you

Drugs truly rewire the brain. Even a one-time abuser will have decreased brain activity due to the extreme releases of dopamine. Because of this, the brain tries to compensate for large release, so the brain needs even more the next time to get high. All of the brain is affected by drugs, even the decision making, judgement, memory and movement parts. Another consequence of this rewiring is the subconscious seeking for drugs.
Also, immense health effects are incurred. Heroin and alcohol both cause constriction of the airways, which can easily lead to death, especially when combined. Heroin constricts the airways by increasing levels of the inhibitory GABA, while alcohol decreases the excitatory glutamate to constrict the airways. Alcohol can also cause unconsciousness and vomiting. All stimulants can cause heart attacks, overheating, and brain damage due to popped blood vessels. All smoking can cause lung cancer, throat cancer, esophageal cancer, and strokes.