In this lab, I started by doing a controlled experiment. The control consisted of a 1/4 tablet of Alka Seltzer being dropped in 10 mLs of room temperature vinegar. For each test after that, I changed one variable. For the temperature test, instead of room temperature vinegar, I used vinegar that had been heated, and vinegar that had been cooled over ice. For the surface area test, I did one test with a 1/4 tablet of alka seltzer that had been crushed, and another test in which a 1/4 tablet of alka seltzer that had been ground into dust. For the vinegar concentration tests, I did one test in which I used 5 mL of water, and 5 mL of vinegar. For the second test of concentration, I used 2.5 mL of vinegar, and 7.5 mL of water. It is important that I first created a controlled experiment, so that I could compare the results of the experiments to how Alka Seltzer normally reacts. The procedure was effective in determining how each variable influenced the rate, because I only changed one variable at a time, whilst keeping the other conditions the same. If I had changed more than one variable at a time, I would not be able to obtain accurate results.
By changing the temperature of the vinegar, the particles will move faster or slower, depending whether or not the temperature of the vinegar is increasing or decreasing, and the particles may collide more often, so they will react quicker. By decreasing the amount of vinegar, the Alka Seltzer will react slower because t is apparent that the Alka seltzer reacts better in vinegar than it does in water. If the tablet is crushed, there is more surface area, so more of the particles will be colliding more often, so the reaction will speed up.
Enrichment: An example of a biological catalyst is Amylase. Amylase is found in saliva, and it helps any ingested starches break down into simple sugars. It works like a key, because it helps the saliva molecules fit to starch molecules, in order to chemically break them apart.
Thursday, December 22, 2011
Friday, December 9, 2011
Lab 4.2 Heating and cooling curves
The melting point of Lauric acid is about 45° Celsius. The freezing point is about 45° Celsius. They are the same because they involve phase changes between the same two phases (liquid and solid). The only difference is that heat is being added to reach the melting point, and heat is being removed to reach the freezing point. So they are the same, only in different directions. I determined the freezing and melting points, because on the graphs, the line plateaued at about 45° Celsius. This means that during that time period (roughly one and a half minutes) the Lauric acid was changing states of matter.
On the heating curve, when the substance is in either state of matter, (liquid of solid) the kinetic energy, or temperature of the Lauric acid is increasing. This is because the substance is heating up and the molecules that it is composed are beginning to move faster. The potential energy is at a constant because the substance is not changing phases of matter during this time. This is similar for the cooling curve, only instead of increasing, the kinetic energy (temperature) is decreasing, because as heat is being taken away, the molecules are slowing down. The amount of potential energy is increasing when the Lauric acid is melting, and decreasing when it is freezing. There is more potential energy in a liquid than in a solid, so as it is changing phases of matter, the potential energy is also changing.
Enrichment: The actual melting/ freezing point of Lauric acid is 43.2° Celsius. My results were slightly off because I was only calculating the temperature every fifteen seconds. If i were to record it every second, then the data may have been more accurate. My percent error was 4.17%.
Lauric acid is used to help scientists learn the molar mass of unknown substances. They mix the unknown substance with the Lauric acid and calculate the temperature at which the mixture freezes. The chemical formula is C12.
Source: http://en.wikipedia.org/wiki/Lauric_acid
On the heating curve, when the substance is in either state of matter, (liquid of solid) the kinetic energy, or temperature of the Lauric acid is increasing. This is because the substance is heating up and the molecules that it is composed are beginning to move faster. The potential energy is at a constant because the substance is not changing phases of matter during this time. This is similar for the cooling curve, only instead of increasing, the kinetic energy (temperature) is decreasing, because as heat is being taken away, the molecules are slowing down. The amount of potential energy is increasing when the Lauric acid is melting, and decreasing when it is freezing. There is more potential energy in a liquid than in a solid, so as it is changing phases of matter, the potential energy is also changing.
Enrichment: The actual melting/ freezing point of Lauric acid is 43.2° Celsius. My results were slightly off because I was only calculating the temperature every fifteen seconds. If i were to record it every second, then the data may have been more accurate. My percent error was 4.17%.
Lauric acid is used to help scientists learn the molar mass of unknown substances. They mix the unknown substance with the Lauric acid and calculate the temperature at which the mixture freezes. The chemical formula is C12.
Source: http://en.wikipedia.org/wiki/Lauric_acid
Tuesday, December 6, 2011
Lab 4.1 Having Fun With Air Pressure
1. A becrease in pressure causes the volume of a balloon to increase.
2. Adding more pressure increases the pressure in that bottle.
3. As the volume of a cylinder in increased, the pressure will decrease.
4. Inreasing the pressure in a tire by adding more gas will cause the volume to increase.
5. As the temperature of a closed container of water in increased, the amount of water vapor above the water causes an increase in vapor pressure.
6. As the air pressure of a liquid is increased by adding more air, the boiling point of the liquid will decrease.
7. If a balloon filled with air is taken under water to a depth of ten feet, its volume will decrease.
8. The temperature of a beaker of boiling water will increase as more heat is added.
9. Hot air rises because it is less dense than the cold air around it.
10. When heated, the volume occupied by air in the balloon will increase.
11. The lowest possible achievable temperature in -273 degrees celcius, which is also expressed as 0 degrees kelvin.
12. .88 atm.
13. 130 degrees kelvin is 403 degrees celcius.
Enrichment: The collapse of the tanker car shown in the picture can be explained quite simply. When the men cleaned its interior with hot water, they made the mistake of sealing it. Inside the tanker car, the air particles were mowing very quickly due to the high temperature. As the temperature on the outside of the tanker cooled, so did the temperature on the inside of the tanker. This caused the particle motion isnide the tanker to decrease, lowering the pressure. As the air may have warmer up some throughout the night, the pressure on the outside of the tanker car was greater than the pressure on the inside of it, thus causing it to collapse upon itself.
2. Adding more pressure increases the pressure in that bottle.
3. As the volume of a cylinder in increased, the pressure will decrease.
4. Inreasing the pressure in a tire by adding more gas will cause the volume to increase.
5. As the temperature of a closed container of water in increased, the amount of water vapor above the water causes an increase in vapor pressure.
6. As the air pressure of a liquid is increased by adding more air, the boiling point of the liquid will decrease.
7. If a balloon filled with air is taken under water to a depth of ten feet, its volume will decrease.
8. The temperature of a beaker of boiling water will increase as more heat is added.
9. Hot air rises because it is less dense than the cold air around it.
10. When heated, the volume occupied by air in the balloon will increase.
11. The lowest possible achievable temperature in -273 degrees celcius, which is also expressed as 0 degrees kelvin.
12. .88 atm.
13. 130 degrees kelvin is 403 degrees celcius.
Enrichment: The collapse of the tanker car shown in the picture can be explained quite simply. When the men cleaned its interior with hot water, they made the mistake of sealing it. Inside the tanker car, the air particles were mowing very quickly due to the high temperature. As the temperature on the outside of the tanker cooled, so did the temperature on the inside of the tanker. This caused the particle motion isnide the tanker to decrease, lowering the pressure. As the air may have warmer up some throughout the night, the pressure on the outside of the tanker car was greater than the pressure on the inside of it, thus causing it to collapse upon itself.
Tuesday, November 15, 2011
Lab 3-2 Properties of Ionic & Covalent Compounds
Ionic compounds have higher melting points that covalent compounds. They conduct more electricity, and they dissolve quickly in water.
Covalent substances have lower melting points, and will not conduct as well as ionic substances.
Metals bond with nonmetals to form ionic bonds. They are formed when a metal and a non metal gain/ lose electrons and create opposite charges, so they are attracted to one another.
Covalent bonds occur when two non metals share electrons to create a full outer electron shell in both.Covalent compounds lack the ability to conduct electricity as a solid or in solution, because they lack a charge, and the electrons are not free to move around and carry an electric current.
Ionic compounds conduct electricity as a liquid because the ions are free to move around, and carry an electric current.
Enrichment: Electrolytes are ions in a substance that make that substance electrically conductive. Gatorade advertises that their drinks contain electrolytes because electrolytes rehydrate the body. They also help carry signals through the use on electric current. Sodium is the electrolyte used by the body.
Thursday, November 3, 2011
Lab 3.1 Modeling Molecules
I think that ionic bonds are stronger than covalent bonds. I believe this because the melting point for an ionic bond is stronger than a covalent bond. This indicates that more energy is required to break down the ionic bond.
When HCl is melted, it is experiencing a physical change. And thus, the compound is not being broken down in to separate Hydrogen and Chlorine atoms, it is simply changing phystical forms.
Melted ionic substances can conduct electricity because the molecules are free to move aroung and the electrons are less condensed. When an ionic substance is a solid state, the molecules are more compacted and do not move as freely as when in a liquid form.
Molecular substances do not conduct electricity because they are composed of only nonmetals, which are not good conductors of electricity.
Enrichment: A polar molecule is a molecule that has different charges at either end. Water molecules are polar because the Hydrogen end is positive, and the Oxygen end is negative. This effects how the molecules are arranged because the the opposite ends attract.
When HCl is melted, it is experiencing a physical change. And thus, the compound is not being broken down in to separate Hydrogen and Chlorine atoms, it is simply changing phystical forms.
Melted ionic substances can conduct electricity because the molecules are free to move aroung and the electrons are less condensed. When an ionic substance is a solid state, the molecules are more compacted and do not move as freely as when in a liquid form.
Molecular substances do not conduct electricity because they are composed of only nonmetals, which are not good conductors of electricity.
Enrichment: A polar molecule is a molecule that has different charges at either end. Water molecules are polar because the Hydrogen end is positive, and the Oxygen end is negative. This effects how the molecules are arranged because the the opposite ends attract.
This diagram that I have created shows that the positive ends of the molecules attract to the negative ends of the other molecules, and vise versa.
Friday, October 28, 2011
Lab 2.2 Bag of Ions and Periodic Table activities
The Periodic Table is arranged on a grid system, with the columns being groups, and the rows being periods. The elements that are located in the same group have the same number of valence electrons. For example, the elements that are in group 18, all have 8 valence electrons. These elements are the Noble Gases, and they have similar chemical properties. This holds true for the elements in other groups; they have similar chemical properties as elements as other elements in the same group. The major different between elements in the same group, is the number of electron shells. Elements that are in the periods closer to the bottom of the periodic table have more electron shells, thus, the atom is larger. To sum it up, an atom that is in the bottom right corner of the Periodic Table will have a higher number of valence electrons and more electron shells than an element that is in the top left hand corner of the periodic table.
Atoms and Ions are fairly similar. Ions are atoms in a more stable state because they have either gained electrons to make their valence electron count 8, or have lost electrons to bring their valence electron count to 0. This transfer of electrons happens when 2 elements exchange valence electrons such that they will have opposite charges, and will bond together. A Magnesium ion is still Magnesium, it is just Magnesium that has been oxidized. You can predict the charge of an ion based on how many valence electrons it has. If an atom has 3 valence electrons, then its ion will have a charge of +3, because it is going to lose those three valence electrons. One can determine whether the charge of the ion will be positive of negative. Metals will lose their valence electrons, making their charge positive, and nonmetals will gain electrons, making their charge negative; with the exception of the noble gases, which cannot react with anything.
Atoms and Ions are fairly similar. Ions are atoms in a more stable state because they have either gained electrons to make their valence electron count 8, or have lost electrons to bring their valence electron count to 0. This transfer of electrons happens when 2 elements exchange valence electrons such that they will have opposite charges, and will bond together. A Magnesium ion is still Magnesium, it is just Magnesium that has been oxidized. You can predict the charge of an ion based on how many valence electrons it has. If an atom has 3 valence electrons, then its ion will have a charge of +3, because it is going to lose those three valence electrons. One can determine whether the charge of the ion will be positive of negative. Metals will lose their valence electrons, making their charge positive, and nonmetals will gain electrons, making their charge negative; with the exception of the noble gases, which cannot react with anything.
Thursday, October 20, 2011
Lab 2.1 Grouping of Elements
1. The two groups that I created at the end of the lab were metals and non metals.
2. Electrical conductivity is a chemical property because it is related to the subatomic particles (electrons) and how they react with one another. Malleability and appearance are physical properties because they are only how the elements look/appear. The way that the elements look, and the chemical make up of them are unrelated. Chemical reactivity is a chemical property. The name is very self explanatory; this determines if and how the elements reacted with the acid, based on their chemical make-up.
3. Elements that are metalloids are unique because they do not have only the properties of either side. They could exhibit come of the properties of a metal, and at the same time exhibit some properties of a non-metal.
3b. Silicon (Si) is a metalloid.
3c. The 7 metalloids are: Silicon (Si), Boron (B), Germanium (Ge), Arsenic (As), Antimony (Sb), & Tellurium (Te).
4. As you look from left to right on the Periodic Table, you see that the elements listed become less metal-like, that is, with the exception of hydrogen (i.e. Metals, Metalloids, Non-Metals, and finally, the Noble Gases). It seems to be that the elements with more valence electrons are less metal-like, and the elements with less valence electrons are more metal-like, or are metals.
4b. There is a less noticeable trend that appears when looking from the top of the Periodic Table to the bottom. Although the metalic characteristics of elements seem to show a trend from left to right, the Table also shows that, of the first 112 elements, there are more and more metals per row as the period number increases. This shows that elements with more electron shells with exhibit more metalic properties than an element with fewer electron shells.
Enrichment. Gold (Au), number 79 on the Periodic Table, is derived from the Latin word "Aurum" which is a direct translation to the English word "gold". (Bentor, Yinon. Chemical Element.com - Gold. Oct. 20, 2011 http://www.chemicalelements.com/elements/au.html.)
2. Electrical conductivity is a chemical property because it is related to the subatomic particles (electrons) and how they react with one another. Malleability and appearance are physical properties because they are only how the elements look/appear. The way that the elements look, and the chemical make up of them are unrelated. Chemical reactivity is a chemical property. The name is very self explanatory; this determines if and how the elements reacted with the acid, based on their chemical make-up.
3. Elements that are metalloids are unique because they do not have only the properties of either side. They could exhibit come of the properties of a metal, and at the same time exhibit some properties of a non-metal.
3b. Silicon (Si) is a metalloid.
3c. The 7 metalloids are: Silicon (Si), Boron (B), Germanium (Ge), Arsenic (As), Antimony (Sb), & Tellurium (Te).
4. As you look from left to right on the Periodic Table, you see that the elements listed become less metal-like, that is, with the exception of hydrogen (i.e. Metals, Metalloids, Non-Metals, and finally, the Noble Gases). It seems to be that the elements with more valence electrons are less metal-like, and the elements with less valence electrons are more metal-like, or are metals.
4b. There is a less noticeable trend that appears when looking from the top of the Periodic Table to the bottom. Although the metalic characteristics of elements seem to show a trend from left to right, the Table also shows that, of the first 112 elements, there are more and more metals per row as the period number increases. This shows that elements with more electron shells with exhibit more metalic properties than an element with fewer electron shells.
Enrichment. Gold (Au), number 79 on the Periodic Table, is derived from the Latin word "Aurum" which is a direct translation to the English word "gold". (Bentor, Yinon. Chemical Element.com - Gold. Oct. 20, 2011 http://www.chemicalelements.com/elements/au.html.)
Tuesday, September 27, 2011
Lab 1-3 Separating a mixture
In this experimented, the mixture I created was 30% sand, 30% iron, and 40% salt. Right away, it was easy to determine how to separate the homogeneous solution; use a magnet to remove the iron, dissolve the salt in the remaining solution in water, drain the salt water and filter the sand, and finally, boil the salt water to get the solid salt back.
When separating the mixture, there was obviously some room for error. Iron, which was the easiest to separate, had a small percent error, but I was unable to remove all of it, thus, it had 5.47% less than the amount I started with. Sand, on the other hand, was a little harder to separate from the salt water, but when I drained it, it must have still been semi-saturated, for it had more mass after being separated from the solution. As for salt, 'twas very difficult scraping it off the inside of the beaker once boiling out the water. Because of this, there was a very large percent error in the salt category.
To better the process of the separation, I could have let the sand filter out for a longer time. If I had made sure that all of the water was out of the the sand, i would have gotten a better measurement of how much sand I was able to recover.
If after doing the math, there was a non-terminating decimal, I rounded the answer to the hundredths. If the answer did not, I rounded to the tenths.
This related to what we have been doing in class, because we are learning about homogeneous and heterogeneous mixtures, and how they can be changed. We have also been learning about the balance of matter, and how it cannot be destroyed. Thus, we needed to determine what happened to the part of the substances that we did not recover, and where they could have gone.
When manufacturing and purifying a chemical, companies will take other factors into consideration, such as bacteria, foreign minerals, and the pH of the substance. If the pH is balanced to whet it should be, then that indicates that the purification is probably complete. If not, then some more purification needs to be done.
When separating the mixture, there was obviously some room for error. Iron, which was the easiest to separate, had a small percent error, but I was unable to remove all of it, thus, it had 5.47% less than the amount I started with. Sand, on the other hand, was a little harder to separate from the salt water, but when I drained it, it must have still been semi-saturated, for it had more mass after being separated from the solution. As for salt, 'twas very difficult scraping it off the inside of the beaker once boiling out the water. Because of this, there was a very large percent error in the salt category.
To better the process of the separation, I could have let the sand filter out for a longer time. If I had made sure that all of the water was out of the the sand, i would have gotten a better measurement of how much sand I was able to recover.
If after doing the math, there was a non-terminating decimal, I rounded the answer to the hundredths. If the answer did not, I rounded to the tenths.
This related to what we have been doing in class, because we are learning about homogeneous and heterogeneous mixtures, and how they can be changed. We have also been learning about the balance of matter, and how it cannot be destroyed. Thus, we needed to determine what happened to the part of the substances that we did not recover, and where they could have gone.
When manufacturing and purifying a chemical, companies will take other factors into consideration, such as bacteria, foreign minerals, and the pH of the substance. If the pH is balanced to whet it should be, then that indicates that the purification is probably complete. If not, then some more purification needs to be done.
Thursday, September 22, 2011
Lab 1-1 Properties of Green Stuff
I'd like to say that I have lost trust in this site because I just completed this and clicked publish and it did not publish; nor did it save.
Here it goes again...
Twice, now, this has happened.
In this lab, the procedure was the following:
-Observe the green stuff without reaction.
Add 30 mL of water to the green stuff and observe.
Place a drop of this mixture on aluminum foil and observe.
Tera up the foil into the green stuff and observe.
At first, the green stuff was green and in a solid powder form. When mixed with the water, it glowed green, and dissolved into a liquid. When it was dropped onto the foil, it fizzed and released a gas, it turned dark, and dried up into a solid. When all of the foil was in the green stuff and water mixture, all of the liquid fizzed and dried up (the same reaction as above).
I know if a change is chemical if the green stuff changes its state of matter, if it fizzes, or if it burns. An example of a chemical change was when it fizzed after being exposed to the foil. A physical reaction happens when it changes shape, but not it's chemical make up. Solids have a definite shape, and the molecules are tightly packed. Liquids and gasses, however, do not have a definite shape, and the molecules are free to move.
This relates to what we have been doing in class because we are learning about compounds, elements, and mixtures, and how they relate and react to each other.
I would like to see how copper chloride reacts when it is ignited because the wikipedia page says that is glows a bright blue, and that sounds cool.
Here it goes again...
Twice, now, this has happened.
In this lab, the procedure was the following:
-Observe the green stuff without reaction.
Add 30 mL of water to the green stuff and observe.
Place a drop of this mixture on aluminum foil and observe.
Tera up the foil into the green stuff and observe.
At first, the green stuff was green and in a solid powder form. When mixed with the water, it glowed green, and dissolved into a liquid. When it was dropped onto the foil, it fizzed and released a gas, it turned dark, and dried up into a solid. When all of the foil was in the green stuff and water mixture, all of the liquid fizzed and dried up (the same reaction as above).
I know if a change is chemical if the green stuff changes its state of matter, if it fizzes, or if it burns. An example of a chemical change was when it fizzed after being exposed to the foil. A physical reaction happens when it changes shape, but not it's chemical make up. Solids have a definite shape, and the molecules are tightly packed. Liquids and gasses, however, do not have a definite shape, and the molecules are free to move.
This relates to what we have been doing in class because we are learning about compounds, elements, and mixtures, and how they relate and react to each other.
I would like to see how copper chloride reacts when it is ignited because the wikipedia page says that is glows a bright blue, and that sounds cool.
Thursday, September 15, 2011
Lab 1-2 Indirect Measurement
In this experiment, i found that i was able to calculate the thickness of the aluminum foils, as well as the diameter of the copper wire with minimal percent error. The percent errors of the test were; regular foil: -7.6%, heavy duty foil: -17.86%, and for the copper wire: -6.45%. To find the thickness of the aluminum foils, I used what ! know about aluminum, (the density), determined the mass, using the scale, and measured the length and width the best I could. From there, I just used the density formula, and did the simple math do determine themissing variable (the "height" of the aluminum foil).
The copper wire, however, was a little more difficult in coming up with a solution. Assuming that the width and height of the copper wire were the same, (because they were both the diameter, instead of having two separate variables, (X & Y), I had two of the same variable, (2X).. From there, i used the same technique as before, only with different equations and different variables.
When using a ruler, and water displacement to calculate the thickness, you can read them inaccurately. That is why there are limitations to those techniques.
When there are a large number of decimals, we cannot be confident that this is an exact measurement. if we were to use a calculator, it does not know that we are taking measurements on tangable items, and therefore, and it may give a nonterminating decimal. This of course makes no sense, because a measurement has to terminate. So, in this case, we have to round the number, thus, making it slightly inaccurate.
Some sources of error in how i conducted the experiment are: 1. The foil may not be 100% aluminum, and thus could have a different density. 2. Using a ruler, we might not measure correctly. 3. The foil may not be a perfect rectangle, so when measuring, we would have to account for, and subtract the part of the "rectangle" that is missing.
We could use the same method of finding the diameter of the wire in a power line. The only extra steps we would need to include would be determining what materials are included in the power line (copper, Rubber, etc.) and what percentage of the power line they are. Other than those steps, we could use the same simple equations to solve that problem.
The copper wire, however, was a little more difficult in coming up with a solution. Assuming that the width and height of the copper wire were the same, (because they were both the diameter, instead of having two separate variables, (X & Y), I had two of the same variable, (2X).. From there, i used the same technique as before, only with different equations and different variables.
When using a ruler, and water displacement to calculate the thickness, you can read them inaccurately. That is why there are limitations to those techniques.
When there are a large number of decimals, we cannot be confident that this is an exact measurement. if we were to use a calculator, it does not know that we are taking measurements on tangable items, and therefore, and it may give a nonterminating decimal. This of course makes no sense, because a measurement has to terminate. So, in this case, we have to round the number, thus, making it slightly inaccurate.
Some sources of error in how i conducted the experiment are: 1. The foil may not be 100% aluminum, and thus could have a different density. 2. Using a ruler, we might not measure correctly. 3. The foil may not be a perfect rectangle, so when measuring, we would have to account for, and subtract the part of the "rectangle" that is missing.
We could use the same method of finding the diameter of the wire in a power line. The only extra steps we would need to include would be determining what materials are included in the power line (copper, Rubber, etc.) and what percentage of the power line they are. Other than those steps, we could use the same simple equations to solve that problem.
Thursday, September 8, 2011
Cheesy Get To Know You Assignment
My name is Philip Sheehan. Last year I took Regents Biology. I am taking AP world history this year. I have not always lived in RH, I was born in St. Augestine, Florida. Last year i took Geometry. I am now in Algebra 2 & Trigonometry. There is no one thing in particular that i will brag about. I plan on doing something prestigious and highly important for a career and for college. I haven't visited anywhere awesome lately. I don't do any school clubs or activities, however, it is only the second day. That has the possibility to change. I had a job, washing dishes, over the summer, but no longer. I am on a gymnastics team outside of school. I have a pretty basic family; mom, dad, and sister. My parents divorced, and my mom remarried. I do not speak any other languages, but I take ASL III. I am taking chemistry to get the last Regents Science credit. I would like to have a 100% in Chemistry. I do not have a favorite sports team, I tend not to watch sports on TV. I learn quickly when the information being given to me is well explained. I don't mind where i sit in the classroom, as long as it's not in one of the corners. It bugs me when teachers are passive, and not willing to help; also when they are unable to teach well.
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