I. RESEARCH QUESTION: Determine the enthalpy of magnesium with hydrochloric acid.

II. ABSTRACT: By doing a reaction in a controlled, insulated environment and measuring the heat produced or absorbed, one can determine the enthalpy. In this experiment, we will be reacting magnesium with hydrochloric acid and determining the enthalpy for the reaction.

III. SAFETY CONSIDERATIONS: Wear safety glasses.

IV. MATERIALS:

V. PROCEDURE: 

1. Collect all equipment and put on your safety glasses.
2. Measure out 50.0mL of 1.0M HCl and pour into a pre-weighed calorimeter.
3. Record the mass of the calorimeter + HCl.
4. Record the starting temperature of the HCl.
5. Measure out no more than 0.2g of magnesium ribbon. Record the actual mass.
6. Roll up the Mg ribbon into a loose ball. When ready, place the Mg into the HCl. Quickly place BOTH lids on the calorimeter and slide the thermometer probe into the reaction mixture.
7. Record the temperature every 15 seconds, until the reaction is complete (you'll be able to hear the gas being given off when it's reacting).
8. When the reaction is complete, record the final temperature.
9. Rinse off the thermometer probe and pour the reaction mixture into the waste container, with an equal volume of tap water to "neutralize" any remaining acid.

VI. EVIDENCE/CALCULATIONS:

Mass of calorimeter: 29.48g

Mass of calorimeter and HCl: 78.64g

Mass of Mg: .16g

Intial Temperature: 24.3 Celsius

Final Temperature: 39.4

1. Mg + 2HCl -> MgCl2 + H2

2. Q = 49.16g * 14.2 degrees C * 4.2 j/g C = 2931.9024 J = 3000 J

3. 3000/1000 = 3.0 J

4. .16g Mg * 1 mol/24.3050g Mg = .00658 mol Mg

5. 3.0 kJ/ .00658 mol = 455.71875 kJ/mol

6. -801.15 - 2(-167.2) = -466.75 kJ

7. Percent Error: 2.36%

VII. CLAIM:

The enthalpy of magnesium with hydrochloric acid is 455.71875 kJ/mol.

VIII. SCIENTIFIC EXPLANATION:

So to find the enthalpy of reactions, you need to find the mass, change of temperature, and the specific heat. From this you can use various formulas and calculations to further understand reactions. Like applying how many moles of the added substance you use, such as the Mg as above. Through this you can determine how much energy is being absorbed or produced.

The presentation was overall well put together, besides missing the title of the class on the cover page. There was a few problems with verbs and sentence structure. The overall critique focused on the scientific level of the content. Adding details to the dispute concerning enviromental and health benefits, as well as why some would think it is less effective than traditional diapers. Lastly, the majority of the resources were more topical and biased than scientific in nature.

Changes I would plan to make would be recontructing the flow of some sentences. Rereading the paper, I realized some of the wordings were awkward. I would focus more on the science of the content of diapers. This includes specifics on the benefit of biodegradable diapers vs. traditional diapers and the debate on whether which is really better. I would also focus on making my paper more scientific than opinionated, which would require to reevaluate my sources to make sure they're not biased and researched. Lastly, remember to put my class title on my cover page.

I. RESEARCH QUESTION: How are pH and concentration correlated in strong vs. weak acids and bases?

II. ABSTRACT: This experiment was created to determine the correlation between the strong and weak acids and bases. The problem ( or question) would be the what would the pH correlation between them. The method used to carry out this experiment was to perform a serial dilution of strong acid (HCl), strong base (KOH), weak acid (acetic acid), and weak base (NH4OH), in total of 16 tubes ( 4 each).

III. SAFETY CONSIDERATIONS: Safety glasses!

IV. MATERIALS:

• 16 microfuge tubes
• pipettes
• strong acid (HCl)
• strong base (KOH)
• weak acid (acetic acid)
• weak base (NH4OH)
• distilled water
• pH paper strips

V. PROCEDURE:

1. Obtain 0.1M solutions of a strong acid (HCl), strong base (KOH), weak acid (acetic acid), and weak base (NH4OH).
2. Working in microfuge tubes, perform a serial dilution with each solution so you end up with 0.1M, 0.01M, 0.001M and 0.0001M solutions for EACH solution provided (4 solutions x 4 dilutions = 16 tubes total).
3. Make sure your tubes are labeled as you go!
4. Determine the pH of each solution by adding ONE DROP to a strip of pH paper. (alternatively, you may use the SPARK pH probe to determine pH)
5. Then, calculate the [H+] for each solution.
6. Calculate the pOH and [OH-] of each solution.
7. Identify the solution as ‘strong’ or ‘weak’.
8. Create a total of 4 line graphs; two for the acids (one strong, one weak) and two for the bases (one strong, one weak). Graph the concentration of the acid (expressed as 1x10-n) vs. [H+].

I. RESEARCH QUESTION: Can we use colorimetry to verify Beer's Law?

II. ABSTRACT: This experiment was conducted to better understand and verify Beer's Law using colorimetry. The problem we were addressing was whether Beer's Law was accurate, which states that the absorbance is directly proportional to the concentration of a solution. In order to solve the problem, methods we used was diluting the mixed solution, figured the absorbance level with the SPARK system, and then graphing the level of concentration vs the absorbance. Results were pretty accurate and correlated, with the graph consistently curving with the appropriate ratio. The overall conclusions verified Beer's Law through the consistent results with corresponding levels of absorbance and concentration.

III. SAFETY CONSIDERATIONS:

• Wash your hands before and after the experiment
• Wear your handy dandy safety glasses for safety precautions

IV. MATERIALS:

• Copper Sulfate
• 6 test tubes
• pipettes
• graduate cylinder
• flask
• cork
• distilled water
• SPARK system

V. PROCEDURE:

1. Before you begin the lab, you need to set up and fill in a chart figuring out the appropriate amounts needed to use for the solutions (creating a standard curve). The chart should consist of the concentration and volume of stock solution, volume of distilled water, and the concentration and volume of final solution. 
2. Proceed by making 25.0 mL of "stock" 0.50M CuSO4 solution.
3. Using your data chart, make 5+1 dilutions.
4. Calculate concentrations of each solution, record
5. Analyze with the SPARK colorimetry (red absorbance)

VI. EVIDENCE COLLECTED:

Creating a graph would also be an adaquate piece of evidence, with the concentration of the final solution on the x-axis and the red absorbance level on the y-axis.

VII. CLAIM: By using colorimetery, we were able to verify Beer's law.

VIII. SCIENTIFIC EXPLANATION: Beer's Law states that the absorbance is directly proportional to the concentration of a solution. When graphing the concentration level of the final solution and the red absorbance, the points create a standard curve which directly correlates the amounts of absorbance to the concentration. The data in the table is also clearly evident, as the level of concentration increases, so does the red absorbance. With the verification of Beer's Law, it could be applied to other areas of chemistry as it is proven to be effective and an accurate statement.

I. RESEARCH QUESTION: How do we measure the concentration of a solution using the technique colorimetry?

II. ABSTRACT: This experiment was conducted to familiarize us with using the SPARK system as well as testing and making a standard serial dilution. The focus of the lab was to figure out how many dilutions were needed to reach 100% transparency. To test that we had to use the technique colorimetry, which simply looks at how concentrated a solution is in terms of its ability to allow light to shine through. The major results obtained were any type of transparency was not seen until the third solution. We finally reached a 100% transparency later in the sixth solution. Overall conclusions would consist of concluding that past 0.00001mL of the liquid bluing mixed with distilled water results in 100% transparency. Also that colorimetry is more simple technique to display transparency levels.

III. SAFETY CONSIDERATIONS: Wearing eye protection is important to avoid any or all possibilities that the liquid bluing solution does not contact with the eye.

IV. MATERIALS:

• liquid bluing solution (blue iron suspension)
• dilution well plate
• plastic dropper
• distilled water
• 10 - glass water
• Pasco SPARK w/colorimeter
• glass cuvettes

V. PROCEDURE:

1. Label your test tubes 1-10.
2. Place 5mL of liquid bluing in test tube #1. This is the 100% solution.
3. Take 0.5mL (12 drops) from test tube #1 and put it into test tube #2. Using a clean dropper, add 4.5mL of distilled water to the 0.5mL of orginal solution.
4. Test tube #2 should now have 0.5mL of the first solution and 4.5mL of distilled water. This is your 0.1 solution.
5. Repeat this dilution process until you can barely see the blue dye in the test tubes. Record the concentrations of each dilution in the space below.

VI. EVIDENCE COLLECTED:

VII. CLAIM: By diluting the solution each time we can use the SPARK system and colorimetry to figure out the transparency percentage of the concentration.

VIII. SCIENTIFIC EXPLAINATION: Using the colorimetry technique is a simple and effective way to configure the transparency level of concentration within a solution. As the evidence shows, the SPARK system had zero tranmittance the first two test tube solutions. With each test tube, the transparency level increased, concluding that the #6 solution reached 100% transparency (testing #7 for good measure). The evidence had consistent results, proving that colorimetry is a well tested technique and could be beneficial for other area of studies in chemistry.

Why has the Standard Model become such an important tool for scientists?

It is used as a basis for building, describing, and categorizing particles.

How are subatomic particles are classified?

Often they are classified by their spins.The classes are fermions, quarks, leptons, and bosons.

Update or modifications coming up anytime in your lifetime?

No idea. On one of the websites though, they stated that they have not found one for gravity, yet I thought I saw on our worksheets that graviton was one? Am I crazy or is that something we can look forward to?

September 6, 2011

Density Lab