04/25/12

http://www.cmmap.org/images/learn/clouds/convection.jpg

Here is a picture of hot and cold air. Hot air rises while cold air sinks. Cole air is denser than hot air. This is why gravity makes hot air balloons rise. The denser cold air is pulled down and under the less dense hot air. The molecules are packed closer together in cold air. Hot air moves more than cold air. Technically, both are moving at the same “speed” since it is simply the movement of energy by a process. Dry air is denser compared to water vapor or humid air at the same temperature and pressure. The two components in dry air are Oxygen and Nitrogen with a combined molar mass of 28.97. The components of water are Hydrogen and Oxygen with a molar mass of 16. Hence, water vapor is lighter than dry air.

April 13, 2012

                

                            Caffeine Molecule                                 Cocaine Molecule

Both the caffeine molecule and the cocaine molecule are made of the same atoms. The formula for Cocaine is C₁₇H₂₁NO₄ and the formula for caffeine is C₈H₁₀N₄O₂. Both molecules are made from the same atoms but the configuration of how they are bonded is how each is their own species.             

April 12, 2012

The energy content (density) of materials is a very important characteristic to meet our energy demands. Human activities are dependent on several forms and sources of energy to perform work. The energy content of an energy source is the available energy per unit of weight or volume. Thus, the more energy consumed the more work that can get done. There are four types of physical work related to human activities which include: modification of the environment, appropriation of resources, processing resources and transfer. Based on the thermodynamic concepts we can rate the following from highest to lowest.

Gasoline: 45.4 MJ/Kg

Compressed Natural Gas (CNG): 53.6 MJ/Kg

Ethanol: 30.0 MJ/Kg

Lithium Ion Battery: 0.72 MJ/Kg

March 26, 2012

The problem: I started with 2.0 grams of salicylic acid and 5 grams of acetic anhydride and I got 2.1 grams of acetylsalicylic acid (aspirin). What is my theoretical yield and my percent yield? The process to solve this should be as follows:

1.       Write balanced equation

2.       Calculate number of moles in 2.1 g of salicylic acid (SA)

3.       Calculate moles of acetic anhydride

4.       Based on the amounts of reagents specified in the experiment, calculate the theoretical yield of aspirin

5.       Solve actual divided by theoretical multiplied by 100 to get the percent yield.

C₇H₆O₃ (salicylic acid) + C₄H₆O₃ (Ethanoic anhydride) à C₉H₈O₄ (Aspirin) + C₂H₄O₂ (Acetic Acid)

1 mole of SA produces 1 mole of aspirin which gives this equation a 1:1 ratio.

To calculate the number of moles of aspirin, do the following calculation:

0.0152 mole SA  X  (1 mole aspirin/ 1 mole of SA) = 0.0152 mole aspirin

Then calculate the mole of aspirin to the number of grams of aspirin.

                0.0152 mole aspirin  X  (180 grams SA/ 1 mole aspirin) = 2.74 grams aspirin

The number of moles just calculated is the theoretical yield and now you can solve for the percent yield.

% Yield = (Actual/Theoretical) X 100

(2.1 grams Aspirin)/(2.74 grams Aspirin) X 100 = 76.6 %

March 19, 2012

On March 19, 2012, we discussed limiting reagents and how it relates to making a hamburger. We had to make one double hamburger with bacon and cheese and the formula was as follows: 1 Hamburger bun + 1 Hamburger Patty + 2 Slices of Cheese + 4 Slices of Bacon = 1 Quarter Pounder. We had 10 pounds of Hamburger, 5 pounds of cheese, 4 pounds of bacon and 4 dozen buns. What we are looking to do is figure out what ingredient is the limiting reagent, or which ingredient will get run out of first when making the hamburgers. My process of figuring out how many hamburgers can I make started out by solving for how many buns I have and the number of hamburgers that can go on the buns. After this, I moved on the cheese and bacon. The first piece of information I needed was how many slices of cheese I could get from 5 pounds so in order to do so I looked up how much 1 slice of cheese weighed. This helped with the conversion factors to solve for how many slices of cheese I have. Next, I performed a similar process with the bacon. I researched how many slices of bacon I could get from 1 pound. The number of slices depended on if it was thick or thin sliced. Once I knew how many slices, the conversion factor was used and I determined the maximum number of bacon slices I will have to make as many hamburgers as possible. The maximum number of burgers depended on if you were looking at the bacon or cheese as the limiting reagent. When using thin strips over thick strips of bacon, more strips could be used and therefore more burgers could be made. This also affected weather enough cheese was available as well. I calculated how many hamburgers I could make from using thin strips of bacon so therefore bacon was the limiting reagent. I do not remember the exact number of burgers I estimated but this was my processing.

For the reaction of 2 moles of hydrogen and 1 mole of oxygen resulted in 2 moles of water, I was trying to determine the which is the limiting reagent and how much product can be made beginning with 8.5 grams of hydrogen and 40.2 grams of oxygen. The following steps can be used:

1.       Write balanced equation

2.       Calculate moles of reagents

3.       Determine limiting reagent

4.       Calculate moles of products

5.       Calculate mass of products

6.       Mass Collected

Here is the work following along with the above steps.

1.       2H₂ + O₂ à 2H₂O

2.       Moles=mass/molar mass

Moles H₂= 8.5grams/(2grams/mole)= 4.25 moles H₂

Moles O₂= 40.2grams/(32grams/mole)= 1.256 moles O₂

3.       Limiting Reagent

Two (2) multiplied by 1.256= 2.513 moles O₂

The excess of H₂ means that O₂ is the limiting reagent.

2         Moles of H₂O produced (based on limiting reagent)

1.256 moles O₂ multiplied by (2 moles H₂O/1 mole O₂)= 2.513 moles H₂O

3         Mass of H₂O

4         250 moles H₂O multiplied by (18.0 grams H₂O/1 mole O₂)= 112.5 grams of H₂O

5         Amount of H₂ remaining

4.25 – 2.513 = 1.738 grams H₂

Final Answer:

112.5 grams of H₂O

Oxygen is the limiting reagent

1.738 grams of H₂ product remaining

In Chemistry on Friday March 2, 2012, we were reviewing some of the different reactions we have been practicing in class and on OWL assignments. Some of my favorite chemical equations include precipitate, acid and base, gas forming, double replacement and redox. These are a few of the basic equations used in chemistry and it is important to understand the basics before moving on to the more complicated tasks. Below are examples of each of the following that were listed above.

Precipitate:

ZnBr₂ (aq) + 2AgNO₃ (aq) --> Zn(NO₃)₂ (aq) + 2 AgBr (s)

                2AgBr à 2Ag ⁺ + Br^-

Gas Forming:

Mg (s) + 2 HCl (aq) --> MgCl₂ (aq) + H₂ (g)

Double Replacement:

(NH₄)CO₃ (aq) + AlCl₃ (aq) --> NH₄Cl (aq) + Al₂(CO₃)₃ (aq)

Acid/Base:

2NaOH (aq) + H₂S (aq) --> Na₂S (aq) + H₂O (l)

                2OH^- + H₂S à S^2- + H₂O

H₂CO₃ (aq) + NaOH (aq) --> Na₂CO₃ (aq) + H₂O (l)

On Thursday February 23, 2012, we completed a Chemistry lab called Ion Combination which involved mixing solutions, solving out double replacement reaction equations, and net ionic equations. While completing this lab I was not surprised by any of the reactions and how precipitations were formed because I have completed a lab like this in AP Chemistry at my high school. Our lab consisted of solutions that were unlabeled and we had to combine the solutions and analyze the precipitates formed to figure out what we were mixing due to products of the reaction. An observation that led me to believe a chemical reaction was occurring is that a precipitate had formed. There were also color changes that occurred when mixing the two solutions together. These are sure signs that a chemical reaction has occurred. Also when we used the molecular substances and combined those, a chemical reaction had occurred because there was a temperature change and a gas had formed; both of which are another way of knowing that a chemical reaction has occurred. When combining solutions, there were reactions that produced different product states.  Different product states would include when two liquids were combined to form a solid precipitate. Another would include when we combined the two solutions and a gas developed. All of these observations we can conclude from this Ion Combination Lab. When sodium chloride (NaCl) is added to water (H20), the sodium and the chloride dissociate from each other resulting in sodium + ions and chloride - ions. The chemical disassociation equation would be:
NaCl -> Na+ + Cl-

                On Wednesday February 15, 2012, two of the main topics we discussed were Coulomb’s Law exam topic reviews and naming compounds.

Coulomb’s Law is the idea that as ion charge increases, the attractive force increase and as the distance between ions increases, the attractive force decreases.

Force=K(charge q1)(charge q2) / distance

NaCl, Na+ and Cl- -> melting point 804 degrees Celsius

MgO, Mg+ and O2- -> melting point 2800 degrees Celsius

The attraction between the particles is greater which means higher melting point.

Acetaminophen: This is an active ingredient of Tylenol, C₈H₉NO₂                      

Caffeine: This is located in drinks such as soda like the Pepsi in my refrigerator, C₈H₁₂N₄O₃

Fructose: This is a sugar found in fruits, such as the pineapple in my refrigerator, C₆H₁₂O₆

Isopropanol: This is the main component in rubbing alcohol, C₃H₈O

Methylpyrazine: Is used as flavor in bakery goods and chocolate products from Valentine’s Day, C₅H₆N₂

Ionic compounds tend to have higher melting points because the greater the force of attraction between the particles or as the ion charges increase means it will take more force for the change of state.

Today on Chemistry the main topic we discussed was the atom. The atom has three main pieces that contribute to the entire structure of the atom. There are three pieces within an atom including the proton, neutron and the electron. A proton is located in the nucleus or the center of the atom with positive charge. A neutron, also located in the nucleus, has no charge. Electrons are the third contributing factors with in an atom. They move around the nucleus in a circular direction in the electron cloud and have a negative charge. Electrons behave like light by moving in waves, and have a little bit more mass than a photon. When examining the Iron (Fe) atom, all atoms are made up of spheres that are filled with “heavy” light. It should be noted that the radius of the atom is a thousand times greater than the radius of the nucleus.

The four fundamental forces of our universe include strong nuclear force, weak nuclear force, electro-statics and gravity. The two forces that we most commonly feel and experience everyday are the electro-statics and gravity.

                In one situation with the following liquids: water, ethanol, oil and corn syrup, the densities would form multiple layers due to varying density numbers. Water’s density is 1.0 g/cm3, ethanol’s density is 0.789 g/cm3, oil’s density is 0.8 g/cm3, and corn syrup’s density is 1.33 g/cm3. With the following data we can organize how the liquids will settle within a container. The heavier the density, the liquid would settle to the bottom of the container while the lighter the density will cause the liquid to be suspended on the top of the other liquids. By using the previous rules, the order of the liquids from bottom to top is corn syrup, water, oil and ethanol.

                In another situation where two liquids of different densities will form one layer the liquids would include water and alcohol. Water’s density is 1.0 g/cm3 and alcohol’s density is 0.79 g/cm3. If these two liquids were added to a container together, they would mix together to form one layer. This is commonly shown with standard bottles of drinking alcohol.

                The density of osmium is 22.61 g/cm3. The density is lead is 11.32 g/cm3 and the density of aluminum is 2.70 g/cm3.

At this point, I do not have any comments on the material we are working on. My only question is from the OWL homework on scientific notation. The result continued to be zero or error even after calculating it out multiple times so I would like some help on this question. Other than this one issue, I do not have any other questions or comments at this time.

Today’s main topics included temperature, states of matter and density. There are three different ways of measuring temperature which are Celsius, Fahrenheit, and Kelvin. There are also three states of matter: solid liquid and gas. Gas has the highest temperature and a greater range of motion compared to solids. One single important note to remember is that both solids and liquids are condensed phases. We talked a little about density that water when frozen it is less dense than liquid water, hence the reason why it floats. This was really the only density topics we discussed in class today.

There are a few main differences between absolute scale and relative scale. Relative scales mean that they vary and change with their surroundings. Absolute scale means that there can be several limitations since they are absolute and never change. For example, a relative scale measurement of miles per hour would be 70 mph. The absolute scale of miles per hour would also include the rate at which the Earth is turning in 24 hours which is 1,000 miles in one hour, therefore making the absolute value 1000 + or - 70 mph. For temperature Celsius and Fahrenheit scales are relative. The Kelvin scale is absolute for molecular motions.

We are also asked to include questions and things we are wondering about. I do not have any questions pertaining to the lecture we talked about today. I am wondering what the next topics we will be discussing on Wednesday and Friday. I completed the OWL assignments for February 1, 2012 and then within the next few days, I hope we will find out if the other homework needs to be completed by February 3^rd.

A number of topics that we covered in Chemistry were elements, the periodic table, where elements are located on the periodic table, and finally what the numbers of an element mean such as atomic number, mass etc.

I have taken AP Chemistry in high school and last year we had a summer assignment to do that included talking about the periodic table, elements and their charges. We also did the experiment with balloons of hydrogen and oxygen while discussing the bonding of multiple elements. Although I have discussed and seen these topics before it was still a nice refresher of what is to come in Chemistry.

A few ways to identify if a chemical reaction is occurring would include a gas is produced, formation of a precipitate, change in color, or transfer of energy (heat and/or light), and the change is irreversible.

I do not have any questions about the material covered today but I am looking forward to when we can began working in the chemistry lab completing experiments and working on a little more difficult assignments such as Stoichiometry, Titrations, Equilibrium and Thermodynamics.

Chemistry is the science of matter and molecules and the changes they undergo during chemical reactions. Everything in the world is made of chemical elements and the molecules they form. By studying chemistry, we can understand the making of aspects in our everyday lives. Chemistry is seen in most fields but especially sciences and medicine. As a pre-veterinarian student, chemistry is important because vets are certified to administer pharmaceuticals and other medical prescriptions, which it is their responsibility to know the drugs, what they contain and any affects that will occur to the animal when administered. A chemical molecule that I feel is important in my career of veterinarian medicine would be water, H₂0. If the world did not have water, humans and animals would not survive. Water is a basic necessity for all living organisms. If there came a time when no animals were around, veterinary science would become nonexistent for the soul reason that animals are the building blocks to this medical field.