Cyclohexane Experiment

Potential error could result in when quantitatively transferring in any step and spillinng or not transferring all of any given solution. When diluting each flask has a different level for where its specific volume is, so overfilling the flask is possible when not being focused on. The condition of each penny can impact the results by if some copper was chipped off, or if anything attached to the pennies could impact test results. All of these could result in a different than desired copper percentage. It is important that the absorbance of each penny be within the range of absorbance the calibration curve has. This is because the curve created for this lab was made with 0.00 – 10.00mL of Cu^(2+)stock solution when using those values idealy this curve should therefore be 0-100% copper percentage. If values were found outside of this calibration curve then there would be problems with either calculations or a different curve would be needed to properly record

The purpose of this experiment was to practice the functional group transformation procedure. The process of the experiment included the dehydration of 2-methylcyclohexanol in the presence of phosphoric acid and heat. The products that were formed from the reaction were 1-methylcyclohexene and 3-methylcyclohexene. The mass of the final product solution was 0.502g with a percent yield of 18.7% and a boiling point range of 84.5-98.5oC.

In the hood, place the copper wire in 10mL of nitric acid and wait for it to dissolve. Afterwards, add 100mL of deionized water to the solution and boil the solution, so all the nitrogen oxides are removed. Place the solution to a 250.0mL volumetric flask and add deionized water to the flask until the solution is 250.0mL. When the solution in the flask is at 250.0mL place the solution in a clean plastic bottle. Now cut a penny into four pieces, and measure the mass of all the pieces together. Go back to the hood, and place the pieces of the penny into a 250mL beaker. Afterwards, add 20mL of concentrated hydrochloric acid. Wait for the hydrochloric acid to dissolve the zinc core. When the zinc has dissolved, filter the solution through the filter paper, and place the copper metal pieces into a clean 150mL beaker. In the hood, place 4mL of concentrated nitric acid in the beaker, and when the copper dissolves add, one drop at a time, 30mL of 6 M ammonium hydroxide to neutralize the nitric acid. Transfer the copper/ammonia solution to a 100.00mL volumetric flask. Prepare four different calibration

Weight 30 dry pre-82 pennies which get 89.77g, using 30ml initial volume measuring the volume of 30 pennies, record the data 10.0ml. Using equation Density= Mass/Volume, get the density of the pre-82 pennies is 8.98g/ml. Then calculate the error%=0.10%, and the deviation%=1.29%.

The goal of this experiment was to successfully measure three different coppers and find the density using its mass and the volume of the water in the graduated cylinder. My group decided to keep the volume of water the same instead of having different volumes, which could of made our outcomes different. The accepted value for copper is 8.96 grams over milliliters (John Jay Faculty, 2017). However, my group got numbers such as 9.8 g/ml, 13.8 g/ml, and 8.1 g/ml. The closest result was copper #3, while the other #1 and #2 were off by a few numbers.

After performing the experiment, the results were that copper pennies have a greater density and mass than the zinc pennies. These results supported my hypothesis of since copper has a greater density than zinc, then the copper pennies will have a greater mass than the zinc pennies. Some errors that occurred during this experiment are the non-precise measurement of the water and how some of the copper pennies had grime on them because they were old. This extra grime caused the mass of the pennies greater. A precise measurement of 15 mL of water and clean copper pennies would improve the experiment and the amount of errors would be

After conducting the experiment by trying to find the density of the post-1982 pennies. The average density found after doing the experiment was 7.042 g/mL. The density of zinc is 7.13 g/mL. However, errors may have occurred tampering the density that was discovered. For example, reading the water measurement slightly wrong when using water displacement to find the volume of the pennies or not placing the pennies correctly in the cylinder which could create air pockets .Due to the close difference between the

1. Purpose: to clarify the mechanism for the cycloaddition reaction between benzonitrile oxide and an alkene, and to test the regiochemistry of the reaction between benzonitrile oxide and styrene.

Data: Starting grams Ending grams Grams Cu Should have been %error of Cu Grams of O initial Cu Cu% O% %error of oxygen 1.992 2.157 1.7232 1.753 1.696 0.269 1.614 86.51 13.49 22.66 Claims: Following the experiment we were able to identify the initial unknown red powder as Copper(I) Oxide. Our percent composition was relatively inaccurate as we found a 1.696% error in Copper and 22.66% error in Oxygen.

The pennies that were dropped into the graduated cylinder could have caused some of the water to splash out of it. This may have caused an error in measuring the volume, this would have caused the volume measured to be less than the actual volume, thus allowing the density of the pennies to increase, causing the lab results to be uneven. Another source of error has to do with the mass of the pennies. After the pennies were taken out of the graduated cylinders filled with water, there was still some water droplets left on the pennies when put on the triple beam balance. This extra weight of the water may have caused the measurement in the mass of the pennies to be more than they actually were. This outcome could have caused the density of the pennies to be increased as well, making the lab results inconstant. Any type of coating, for example rust, on the penny may affect the mass. This will add to the mass making it higher, and since density is proportional to the mass, the density will be calculated higher than what it actually

The distillation that was more efficient at separating the two compounds was the cyclohexane and the p-xylene since the curve of the graph for temperature vs. volume has a slightly better curve (Table 4A). The graph for cyclohexane and toluene was more linear (Table 4B). Furthermore, the mole fraction of cyclohexane and p-xylene was higher than the mole fraction of cyclohexane and toluene. For instance, the mole fraction of cyclohexane and p-xylene (when adding the mole fraction of the first ml and the last couple of drops) was 0.6604 while the mole fraction for cyclohexane and toluene was 0.13396. A higher mole fraction means that the compounds were purer which means that they separated better—since increasing the mole fraction increases the vapor pressure. Therefore, my hypothesis was supported.

To prepare and purify an ester: 1-pentyl ethanoate, using pent-1-ol and ethanoic acid. An annotated reaction showing this reaction is shown below:

The yield of the first step, after purifying the cyclohexene, was 66.4%. This is not a very high yield. To confirm that it was cyclohexene and not cyclohexanol, it was put through an IR- spectrometer. The OH broad peak at about 3350 is not very deep, so we can be sure that most of the clear liquid in the bottle is cyclohexene, rather than cyclohexanol. The next step’s yield was even lower than the first, at 7.02%.

This experiment was performed to observe differences in density based on the chemical makeup of an object. Pennies minted before 1982, pennies minted after 1982, and an unknown metal sample was tested to see if there were any differences in their densities. Ten pennies from each category and the metal sample were weighed using a scale to find mass and the displacement method was used to find their volumes. The masses and volumes were then used to calculate the densities of the pennies (D=m/v). The density of the pre-1982 pennies were 8.6 g/mL while the post-1982 pennies were 6.9 g/mL. The metal sample’s density was 1.7 g/mL. Following the experiment we were given the real densities of each item to calculate the percent error with the formula

Furthermore, the measurements from a wooden block and a metal object were taken to calculate their volume and density. In this case, the calculations were more precise but due to other sources of errors, which may be systematic, random or personal, the data was not 100% accurate. There are always certain uncertainties associated with any type of measurement and it is important to know that no measurement will be one hundred percent correct.