Introduction
Yeasts are microorganisms. They can break hydrogen peroxide down into water and oxygen gas. In this experiment you will investigate yeast activity in acidic, neutral, and basic mixtures. You will observe yeast activity by measuring pressure caused by the oxygen gas they produce.
Problem
How does yeast activity differ in acidic, neutral, and basic mixtures?
Hypothesis
The yeast activity in the acidic mixture will be the greatest because the more acidic something is, the greater reaction will take place.
Results
The acidic mixture was a diet soft drink, and the highest kPa was 118.62 kPa. The neutral mixture was skim milk, and the highest kPa was 111.97 kPa. The basic mixture was stomach antacid, and the highest kPa was 124.04 kPa.
Conclusion
The yeast activity was the greatest in the neutral (skim milk). It raised the most and it took the longest to stop rising. In fact, it was still rising when the lab was over. I think the reason for this is because of the milk. The milk could have had some chemical in it we didn't know about, or it could have had the greatest reaction because it was skim and not regular milk. The yeast activity was the least in the acidic (diet Coke). It rose the least and it stopped rising after only a few seconds. I think if the soda wasn't diet, or if it was a different kind of soda, the reaction may have been different. However, the stomach antacid had the highest kPa, and the skim milk had the lowest. My hypothesis was incorrect; I thought that the diet soft drink would have the highest kPa, and the stomach antacid would have the lowest. In reality, the Coke's kPa was right in the middle, and the stomach antacid's kPa was the highest.
Wednesday, March 23, 2011
Thursday, March 17, 2011
Conservation of Mass Lab Investigation
Introduction
Pop rocks are known as the exploding candy, and if you ate Pop Rocks as a kid, you probably remember the legend...if you eat Pop Rocks and then drink a soda, you'll explode. The Food and Drug Administration even set up a telephone hotline to assure anxious parents that the popping candy would not cause children to explode. While you can mark this one up as an urban legend (in other words, it's not true), there is some interesting science behind the world famous popping candy.
Problem
Will there be a chemical reaction between Pop Rocks and soda, and Pop Rocks and vinegar?
Hypothesis
The balloon will fill up with gas because of the carbon dioxide in the Pop Rocks reacting with the chemicals in the soda and in the vinegar.
Results
With the soda, the balloon expanded more rounded and not as tall. It was a potential chemical reaction, meaning it needed to be shook a little for a reaction to take place. Once we started shaking the soda with the Pop Rocks, the balloon almost immediately started expanding. It took about 3 minutes for the balloon to stop expanding. With the vinegar, the bottle didn't need to be shaken, because it just started reacting immediately. The balloon also expanded taller and less rounded than the soda one.
Conclusion
My hypothesis was correct; the balloon did fill up with gas. The gas that it filled up with was the carbon dioxide that the Pop Rocks released when they exploded in the water. While doing the vinegar test, while putting the balloon on the empty soda bottle, the bottle tipped over and the vinegar spilled out. I think we may have gotten a different reaction if that didn't happen, because with the vinegar spilled out some of the chemicals in it. We also had an uneven amount of vinegar and water. If that didn't happen, I think there would have been a chemical reaction, and the balloon would blow up even bigger. For the soda test, I think the type of soda had an effect on the reaction, because some sodas have more chemicals in them than others.
Problem
Will there be a chemical reaction between Pop Rocks and soda, and Pop Rocks and vinegar?
Hypothesis
The balloon will fill up with gas because of the carbon dioxide in the Pop Rocks reacting with the chemicals in the soda and in the vinegar.
Results
With the soda, the balloon expanded more rounded and not as tall. It was a potential chemical reaction, meaning it needed to be shook a little for a reaction to take place. Once we started shaking the soda with the Pop Rocks, the balloon almost immediately started expanding. It took about 3 minutes for the balloon to stop expanding. With the vinegar, the bottle didn't need to be shaken, because it just started reacting immediately. The balloon also expanded taller and less rounded than the soda one.
Conclusion
My hypothesis was correct; the balloon did fill up with gas. The gas that it filled up with was the carbon dioxide that the Pop Rocks released when they exploded in the water. While doing the vinegar test, while putting the balloon on the empty soda bottle, the bottle tipped over and the vinegar spilled out. I think we may have gotten a different reaction if that didn't happen, because with the vinegar spilled out some of the chemicals in it. We also had an uneven amount of vinegar and water. If that didn't happen, I think there would have been a chemical reaction, and the balloon would blow up even bigger. For the soda test, I think the type of soda had an effect on the reaction, because some sodas have more chemicals in them than others.
Tuesday, March 15, 2011
Chemical Reactions and Temperature Lab Investigation
Introduction
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.
Problem
Does temperature affect chemical reactions?
Hypothesis
The warmer the temperature, the greater a chemical reaction will take place, because there will be more energy stored in the water, and the more energy that's in the water, the shorter the chemical reaction will be.
Results
Cold water - The cold water started at 6.7°C and ended at 2.8°C. The reaction took 2 minutes and 30 seconds to end completely.
Room temperature water - The room temperature water started at 22.2°C, and ended at 23°C. It took 34 seconds for the reaction to end completely.
Hot water - The hot water started at 31.6°C, and ended at 50°C. It took 21 seconds for the reaction to end completely.
Conclusion
My hypothesis was correct; the warmer the water got, the less time the chemical reaction took to end completely. I think the different times were influenced by the temperature and only the temperature, because each time, we used the same kind of tablet and the same equipment. Therefore, the answer to the problem (Does temperature affect chemical reactions?) would be yes, temperature does affect chemical reactions. I still believe that the reason the different temperatures affected them is because of the amount of energy in the water.
Observations
Cold water - The cold water had the least fizz and the quietest fizzing sound of any of the waters. I think this happened because the cold water had the least amount of energy.
Room temperature water - The room temperature water's amount of fizz was right in the middle of the three waters, and so was the fizzing noise. I think this happened because the room temperature water's amount of energy was right in the middle.
Hot water - The hot water had the most fizz and the loudest fizzing sound. I think this happened because the hot water had the most energy out of any of the waters.
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.
Problem
Does temperature affect chemical reactions?
Hypothesis
The warmer the temperature, the greater a chemical reaction will take place, because there will be more energy stored in the water, and the more energy that's in the water, the shorter the chemical reaction will be.
Results
Cold water - The cold water started at 6.7°C and ended at 2.8°C. The reaction took 2 minutes and 30 seconds to end completely.
Room temperature water - The room temperature water started at 22.2°C, and ended at 23°C. It took 34 seconds for the reaction to end completely.
Hot water - The hot water started at 31.6°C, and ended at 50°C. It took 21 seconds for the reaction to end completely.
Conclusion
My hypothesis was correct; the warmer the water got, the less time the chemical reaction took to end completely. I think the different times were influenced by the temperature and only the temperature, because each time, we used the same kind of tablet and the same equipment. Therefore, the answer to the problem (Does temperature affect chemical reactions?) would be yes, temperature does affect chemical reactions. I still believe that the reason the different temperatures affected them is because of the amount of energy in the water.
Observations
Cold water - The cold water had the least fizz and the quietest fizzing sound of any of the waters. I think this happened because the cold water had the least amount of energy.
Room temperature water - The room temperature water's amount of fizz was right in the middle of the three waters, and so was the fizzing noise. I think this happened because the room temperature water's amount of energy was right in the middle.
Hot water - The hot water had the most fizz and the loudest fizzing sound. I think this happened because the hot water had the most energy out of any of the waters.
Friday, March 11, 2011
ChemThink: Chemical Reaction
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 reaction 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. 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.
10. So to make H2O from oxygen gas and hydrogen gas, the balenced equation would be 2 H2 + 2 O2 = H2O.
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. The balanced equation for this reaction is 2 C2 + O2 = 2 CO2.
14. In the unbalanced equation, there are 1 Cu atom and 2 O atoms as the reactants, and 1 Cu atom and 1 O atom as the products.
15. To balance this equation, we have to add 3 molecules to the products, because this reaction doesn't make lone Cu atoms.
16. When we added a molecule of CuO, now the number of oxygen atoms is balanced but the number of Cu atoms don't match. Now we have to had more Cu atoms to the reactants.
17. The balanced reaction for this equation is 2 Cu + O2 = 2 CuO.
18. The balanced equation for this reaction is 1 CH4 + 2 O2 = 2 H2O + 1 CO2.
19. The balanced equation for this reaction is 1 N2 + 3 H2 = 2 NH3.
20. The balanced equation for this reaction is 2 KCIO3 = 2 KCI + 3 O2.
21. The balanced equation for this reaction is 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 the same before the reaction and after.
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.
Wednesday, March 9, 2011
Polymer Lab Group Investigation
Sizes
Shapes
My second hypothesis was about the different small shapes. I thought that the football would bounce the highest, because it wouldn't land one of its' flat surfaces because it doesn't have any, and it didn't have a very high chance of bouncing on one of its' two corners. I thought that the cube and the pyramid would bounce the same height, because they would definitely land on one of their flat faces or corners, because there are no round parts on cubes or pyramids. The cube had the highest bounce (13 cm), and it also had the same average (11 cm). The pyramid had the lowest bounce (6 cm), and also the lowest average (4 cm). The football's bounce was right in the middle (7 cm), and it's average was the same. I think the reason these things happened was only because of the different shapes, and nothing else.
Observations
Small ball: The small ball was squishy and wet, but it dried fairly quickly. However, it took a shorter time to dry than the medium and large balls. When it was dry, it was soft and solid, and no longer sticky.
Medium ball: The medium ball was somewhat squishy, and it was really wet, and took a longer time to dry than the small ball, but a shorter time than the large ball. When it was dry, it had the same consistency as the small ball and the large ball.
Large Ball: The large ball was squishy and was the wettest out of all of the balls. It took the longest time to dry out of all three balls. When it was dry, it had the same consistency of the other balls.
Small Shapes: All the small shapes felt exactly the same as the small ball.
Large Ball: The large ball was squishy and was the wettest out of all of the balls. It took the longest time to dry out of all three balls. When it was dry, it had the same consistency of the other balls.
Small Shapes: All the small shapes felt exactly the same as the small ball.
Thursday, March 3, 2011
Sodium Silicate Polymer Lab
REACTION
Silicon is a very interesting type of atom. Like carbon, silicon makes four chemical bonds and can branch out in four directions to make long chains. n sodium silicate, the silicon atom is bonded to four oxygen atoms and is not linked in any chains. The ethyl alcohol has just two carbon atoms. When sodium silicate and ethyl alcohol are put together, the silicate particles begin to link up with each other to form long chains as the ethyl groups (sometimes shown as "R") replace oxygen atoms in the silicate ion. Some become cross-linked between chains. Water molecules are byproducts of the formation of the polymerization bond.
QUESTIONS
What characteristics are similar between your two types of polymers you have made? Differences? One difference between the two polymers would be the appearance. The first polymer looked wet and shiny, and the second one looked somewhat rough. Another difference would be the way they felt. The first one felt sticky and very much like Silly Putty, and the second one felt almost exactly like a smooth rock. The first one was also very flexible, but the second one wasn't flexible at all. However, there were some similarities, such as they were both shades of white, and they were similar in shape (circles).
Most commercial polymers are carbon based. What similar properties do carbon and silicon share that may contribute to their abilities to polymerize? Some similar properties are that they have the same number of electrons (4). They are also both very abundant.
Plastics are made of organic (carbon based) polymers. What similarities does the silicone share with plastics? Both silicon and plastic are able to change into any shape.
How did you know that a chemical reaction had taken place when the two liquids were mixed? I knew because it started to become gel-like and it stuck to the stirring rod.
How could you find out what liquid was pressed out of the mass of crumbled solid as you formed the ball? I knew that the liquid was water, because when you ran it under water, its' shape became more changeable.
Compare your ball with those of the other members of the class. How many properties can you compare (e.g., diameter of sphere versus height of bounce)? List and compare them. Some people's ball had bounced a little lower than ours. Our ball bounced 23 cm high, but a lot of people's didn't even bounce 20 cm, but some bounced even higher, like 25-26 cm. All the balls were pretty much the same size and shape.
OBSERVATIONS AND RESULTS
My hypothesis was that when the sodium silicate and the ethyl alcohol get mixed together, they will become a gel-like solid becasue the sodium silicate is denser, and the alcohol isn't, so it will become gel-like, but not totally solid. This mypothesis was correct, because it did become gel-like before it became completely hard.
Monday, February 28, 2011
The Science Of Addiction
Natural Reward Pathways
The brain is divided into several sections, and the reward pathway is in the center of these. The reward pathway controls feelings of motivation, reward, and behavior, but its' main job is to make us feel good when we do things that are necessary for survival, like eating, drinking, and sex. The pathway connects to other important sections in the brain to gather info about what's happening outside of the body, and to strengthen brain circuits and control desirable behaviors. For example, when you are hungry and you see a sandwich, your five senses gather information about your surroundings and send signals to the brain to let you know that there is a sandwich in front of you. Based on the knowledge that if you eat, you won't be hungry anymore, the brain tells you to eat the sandwich. When you eat the sandwich, special neurons in the reward pathway release dopamine, which gives you a little jolt of pleasure, which is your reward for eating the sandwich. As well as rewarding you for performing beneficial tasks, the reward pathway makes sure you repeat this action whenever you can. It does this by connecting to the parts of the brain that control memory and behavior. When the pathway signals these regions, the brain creates the memory that eating food makes you feel good, increasing the chance of you eating food again. When the reward pathway signals the brain's motor center, it strengthens the wirings for behaviors that help you achieve your reward. In the sandwich example, those behaviors would be picking it up, chewing it, and swallowing it. Overall, the reward pathway's purpose is to make sure that we repeat behaviors necessary for survival.
Drugs Alter the Brain's Reward Pathway
Within seconds of entering the body, drugs can cause dramatic changes to the brain's synapses. By passing the five senses and going straight to the brain, drugs can cause intense jolts of pleasure. Drugs affect the brain to so much that the brain must try to adapt. One way it does this is by reducing the number of dopamine receptors at the synapse. As a result, next time the user want to get high, they will need more of the drug. This is referred to as "tolerance." As the brain adapts to the presence of drugs, regions outside of the reward pathway are affected, such as regions responsible for judgement, learning and memory. These regions begin to physically change and become "hard-wired." Once this happens, drug seeking becomes more of a habit or reflex. This is how a drug user becomes a drug addict. Drugs can even cause changes to the brain that are so dramatic, they can be fatal.
The brain is divided into several sections, and the reward pathway is in the center of these. The reward pathway controls feelings of motivation, reward, and behavior, but its' main job is to make us feel good when we do things that are necessary for survival, like eating, drinking, and sex. The pathway connects to other important sections in the brain to gather info about what's happening outside of the body, and to strengthen brain circuits and control desirable behaviors. For example, when you are hungry and you see a sandwich, your five senses gather information about your surroundings and send signals to the brain to let you know that there is a sandwich in front of you. Based on the knowledge that if you eat, you won't be hungry anymore, the brain tells you to eat the sandwich. When you eat the sandwich, special neurons in the reward pathway release dopamine, which gives you a little jolt of pleasure, which is your reward for eating the sandwich. As well as rewarding you for performing beneficial tasks, the reward pathway makes sure you repeat this action whenever you can. It does this by connecting to the parts of the brain that control memory and behavior. When the pathway signals these regions, the brain creates the memory that eating food makes you feel good, increasing the chance of you eating food again. When the reward pathway signals the brain's motor center, it strengthens the wirings for behaviors that help you achieve your reward. In the sandwich example, those behaviors would be picking it up, chewing it, and swallowing it. Overall, the reward pathway's purpose is to make sure that we repeat behaviors necessary for survival.
Drugs Alter the Brain's Reward Pathway
Within seconds of entering the body, drugs can cause dramatic changes to the brain's synapses. By passing the five senses and going straight to the brain, drugs can cause intense jolts of pleasure. Drugs affect the brain to so much that the brain must try to adapt. One way it does this is by reducing the number of dopamine receptors at the synapse. As a result, next time the user want to get high, they will need more of the drug. This is referred to as "tolerance." As the brain adapts to the presence of drugs, regions outside of the reward pathway are affected, such as regions responsible for judgement, learning and memory. These regions begin to physically change and become "hard-wired." Once this happens, drug seeking becomes more of a habit or reflex. This is how a drug user becomes a drug addict. Drugs can even cause changes to the brain that are so dramatic, they can be fatal.
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