Acid Base Lab

At the beginning of the lab my group and I developed a problem and a hypothesis. Our problem was "How does yeast react with acids and bases?" Our hypothesis was "If we mix yeast with various acids and bases, then we will get different outcomes for each one, with the acid producing the largest reaction." After running our tests, my hypothesis was completely incorrect. The first test we ran was the acidic test. We added yeast to the cola and hydrogen peroxide mix and then put on the stopper and swirled it around. Then, we connected the tube and recorded our results for two minutes. At about 130 kPa the stopper popped off. We put it back on and hoped for the best. To our surprise, it rose again to 132.63 kPa. We concluded that the pressure would have been MUCH higher if the top did not pop off. The next test we did was the neutral test, a mixture of silk milk and hydrogen peroxide. This surprisingly had the highest pressure at 177.18 kPa. The pressure popped of of this one too, but this occurred after the test was finished. Our third and final test was the basic test. This reached a pressure of 164.7 kPa, but popped during the experiment. With this one, we also thought that the pressure would be much higher. In my opinion, if the stoppers did not pop, the basic would have the highest pressure, the neutral would have the second highest pressure and the acidic would have the lowest pressure. Unfortunately, we may never know.

Focus Questions:

Q: In which mixture was the yeast activity the greatest?

A: The yeast activity was the greatest in the neutral mixture, because the pressure rose to 177.18. I also know that the yeast activity was the greatest in this one because when the stopper came off, it frothed almost to the point of overflowing. In the other ones when the top popped of the froth disappeared along with the air pressure. During the experiment (with the stopper on), the froth rose to over half the height of the test tube.

Q: In which mixture was the yeast activity the lowest?

A: The yeast activity was the lowest in the acidic mixture, because the pressure rose to 132.63. Also, when the stopper came off there was no foam left at all. The only thing that could be found was the cola at the bottom and the residue along the walls. During the experiment (with the stopper on), the froth barely rose at all.

Q: What can you conclude from the results of the experiment?

A: After the experiment, I can conclude that the yeast reacts best with the base and the worst with the acid. Knowing this, I think that yeast reacts best in a neutral mixture. If a mixture is more basic it reacts slightly less, but if the mixture is more acidic then the reaction will be MUCH smaller.

Conservation of Mass Lab Investigation

Before our lab investigation we developed a problem and a hypothesis. Our problem was "Will a balloon expand with just pop rocks and soda." Our hypothesis was "If we pour pop rocks into a soda bottle, then it will expand the balloon and a similar reaction will happen with the baking soda and vinegar. After the experiment, I partially accepted and partially rejected my hypothesis.

Our results are as follows. The soda and pop rocks produced nothing more than a slight fizzle around the pop rocks. There was only enough gas released to inflate the balloon without expanding it. I did some research and found out why. When pop rocks and soda are mixed, it is a physical reaction, meaning that nothing changes form. The process that pop rocks are made is that under high pressure carbon dioxide is trapped inside of flavored sugar. When it is put in soda, it is simply dissolved, releasing a small amount of gas. When we tested vinegar and baking soda, it produced large white bubbles and a significantly larger amount of gas. The gas produced was enough to fully inflate the balloon. This is because it is a chemical change rather than a physical change. The baking soda reacts with the vinegar to produce carbon dioxide gas, which is why it bubbles when you mix them together. The following shows the reaction:

NaHCO₃(s) {baking soda} + CH₃COOH(aq) {vinegar} --> NaCH₃COO(aq) + CO₂(g) + H₂O(l)

In conclusion, the baking soda released much more gas and produced a much better result than the soda and pop rocks.

Chemical Reactions & Temperature Lab Investigation

Pre-Lab Information:

"In order for a chemical reaction to occur, the particles, atoms or ions, which are reactants, must physically come into contact with one another. Anything that increases the frequency of these encounters will increase the rate at which the products are formed The rate of a chemical reaction can be increased by increasing the temperature of these reactants." - Lab Paper

Lab Investigation:

This lab focused mostly on how well alka-seltzer tablets dissolve in different temperatures of water. We began with a our problem, "How does temperature affect chemical reactions." After reading our pre-lab info and considering our problem, we developed a hypothesis. Our hypothesis was, "If we do three different tests using hot, room temperature, and cold water to melt alka-seltzer, then the hot water will melt the alka-seltzer tablet the fastest. Then we started our tests. We started with the hot water test. The test began at 50˚C. The tablet was placed into the water. The tablet dissolved unevenly and surprisingly, after the tablet was introduced the water temperature rose 4.5˚C to 54.5˚C. Also, the tablet dissolved completely in 39 seconds. Next was the room temperature water. The water started out at 23.8˚C before the test. The tablet was added to the water. We noticed that the alka-seltzer dissolved more evenly in the room temperature water than in the hot water. Much like the previous test, we found a surprising discovery. Instead of the temperature increasing when the tablet was added like it had before, the water temperature actually decreased by .7˚C to 23.2˚C. The tablet took 42 seconds to fully dissolve. Lastly there was the cold water test. The test started at a chilly 2.7˚C before we added the tablet. After we added the tablet the temperature rose 1.9˚C to 4.6˚C. Unlike the other tablets, this one "danced" around the bottom while it dissolved. We also noticed that it left a layer of powder on the top. The tablet took the longest to dissolve in this test at 1 minute 55 seconds. In conclusion, I fully accepted my hypothesis.

ChemThink Chemical Reaction Questions

Questions

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 change 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. 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. 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.

10.

# of atoms in reactants	Element	# of atoms in prouducts
4	H	4
2	O	2

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 + 2 O2 = 2 CuO

14. In the unbalanced equation there are:

Reactants	Products
Cu atoms 1	Cu atoms 1
O atoms 2	O atoms 1

15. To balance this equation we have to add CuO molecules to the products, because this reaction doesn't loan O atoms.

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

17. The balanced equation for this reaction is:
2 Cu + O2 = 2 CuO
That is the same thing as saying:

Reactants	Products
# Cu atoms 2	# Cu atoms 2
# O atoms 2	# O atoms 2

18. What is the balanced equation for this reaction? 1 CH4 + 2 O2 → 2 H2O + 1 CO2

19. What is the balanced equation for this reaction? 1 N2 + 3 H2 → 2 NH3

20. What is the balanced equation for this reaction? 2 KDIO3 → 2 KCI + 3 O2

21. What is the balanced equation for this reaction? 4 Al + 3 O2 → 2 Al2O3

Summary

1. Chemical reactions always involve breaking bonds, making bonds, or both.

2. The Law of Conservation of Mass says that the same atoms must be present before and after the reaction.

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

Borax and Glue Polymer Lab with Corn Starch

DRAWING IN EMAIL LABLED:

BLOCK 1/3-9-11 LAB INVESTIGATION/AUSTIN CLARKE

For this lab we started by mixing borax, water, corn starch, and food coloring. Since there was now corn starch in the borax mixture it smelled different than the other mixture that smelt quite soapy. This mixture smelt sour and rancid. We then added that mixture to the glue to create a similar polymer to the one we made before. When the polymer came out it looked almost identical to the previous polymer. That was where the similarities ended. Unlike the other polymer, it did not bond as well as the other one. It also formed better than the other polymer. We tried bouncing the polymer to see its rebound at room temperature. The polymer rebounded an average of 18.75cm when dropped from 30cm. We then tried the rebound test again after it had been chilled. The average rebound was 6cm. This was puzzling because when we tried this with the other polymer it rebounded higher. When we tested the polymer frozen we found something even more puzzling. It rebounded to an average height of 17.5cm. After the drop tests we conducted stretch tests with the polymer at room temperature, chilled, and frozen. The results were exactly what we had predicted. At room temperature the polymer stretched 7cm, when it was chilled it stretched 5cm, and when it was frozen it stretched 2cm. Nothing went wrong with the test so overall I thought the test went very well.

Sodium Silicate Polymer Lab

Questions:

What characteristics are similar between the two types of polymers you have made? Differences?

A: They are both bouncy, shiny and white. They were also both formed by combining two things to create a polymer. The differences are that the second one we crated is very hard and keeps its shape while the first one was very gooey and levels out over time.

Most commercial polymers are carbon based. What similar properties do carbon and silicon share that may contribute to their abilities to polymer.

A: Silicon and carbon share the ability to bond with nearly anything and give up as many as 4 electrons.

Darklight, Moe. "Silicon vs Carbon." Physics Forum . 13 Feb 2007. Web. 3 Mar 2011. .

Plastics are made of organic (carbon based) polymers. What similarities does the silicone polymer share with plastics.

A: A similarity they share are that they are both based on ethyl or ethyl based products.

Haswell, Christine; Brule, Joe; Icantu, Ismael; Hui, Katty, . "CHEMICAL ENGINEERING - WE'RE ALMOST EVERYWHERE!." Washington.edu. Washington University , n.d. Web. 3 Mar 2011. .

How did you know that a chemical reaction had taken place when the two liquids mixed.

A: I knew it was a chemical reaction when the two liquids changed form from a liquid to a solid.

How could you find out what liquid was pressed out of the mass of crumbled solid as you formed the ball?

A: There are many ways to find out what liquid was lost. You could Google™ the answer or just think that you need to "re-hydrate" the polymer which means that there is not water in it.

Compare your ball with those of the other members of class. How many properties can you compare (e.g., diameter, height of bounce, weight)? List and compare them.

A: Both look white, wax like, were hard to mold, smelled like muted rubbing alcohol, looked marbled before chilled but glossy after.

Results:

"When sodium silicate solution is added to ethyl alcohol, a polymer is formed. Sodium silicate solution contains sodium hydroxide and silicon dioxide. Sodium hydroxide as a strong base. Under these basic conditions, silicate chains form. When ethyl alcohol is added to sodium silicate solution, two oxygen atoms of silicate are replaced by ethyl with loss of water." The ethyl is the cross linker that prevents the long polymer chains of the silicate solution from sliding past each other and acting like a liquid.

Unlike my old polymer, the new one came out powdery like snow. It was bright white and in little chunks. In order to get it into a ball it had to be moisturized with water. We dropped the polymer from 3ocm five times and it rebounded to an average height of 18cm, much higher than the other polymer. We then put it into a refrigerator for just over ten minutes and then tested the height of its rebound again. Much like the other polymer, after it was chilled it rebounded higher than before. It rebounded to an average height of 20cm. Overall, this polymer behaves the same as the other one but feels much different.

Great Discoveries of Chemistry

The most important discovery, to me, is the discovery of the periodic table. Dmitry Mendeleyev was the founder of the periodic table, he discovered the 63 elements that were necessary to be on it. The periodic table was categorized by the weight in each row. In each row, the elements have something in common. The periodic table has lead to many recent discoveries. It helped create many different formulas for drugs and medications, and just the understanding of the subject of chemistry. It has helped create many new elements, by combining the original elements. Oxygen was also another important discovery. It has helped with industrial field, with the making of cell phones, machines, and there is still an endless list of items that have been created just because of oxygen. Joseph Priestly was the discoverer. Radioactivity was discovered by Marie Curie. Radioactivity was the start of something huge. Cancer and other diseases can be cured by it. This lead to the discovery of radium and polonium. Plastic was probably the most used thing in the world, but many people probably don't know how it came to be. John Wesley Hyatt was the creator. "...formulates celluloid plastic for use as a substitute for ivory in the manufacture of billiard balls. Celluloid is the first important synthetic plastic and is used as a substitute for expensive substances such as ivory, amber, horn and tortoiseshell. Later, Leo Baekeland invents hardened plastics, specifically Bakelite, a synthetic substitute for the shellac used in electronic insulation."

*Completed with Hannah LaBreque