1. What is typically the mobile phase in gas chromatography?

2. What affect is expected for retention times in a gas chromatography experiment if the temperature of the column is reduced?

3. If a significant clog in a 30 m capillary column is so severe that it has to be trimmed to 20 m, how will this affect its ability to effectively separate mixtures of compounds?

4. Why is CH2Cl2 the first peak observed in the gas chromatograms for this experiment?

5. If a student submitted a sample of water for GC analysis because they were confused about what was their organic layer and what was their aqueous layer, would a solvent peak be observed in the gas chromatogram of the sample assuming it was analyzed? Remember our gas chromatograph uses a FID.

I need to find the theoretical yield of benzoic acid from this lab experiment. The first part of the experiment involved this formula

C6H5COOH + NaOH ------> C6H5COO-Na+ + H2O where we mixed 30 mL of a stock solution of toluene-benzoic acid mixture and then added 15.0 mL of aqueous sodium hydroxide to seperate the two layers.

In the second part, C6H5COO-Na + Hcl-------> C6H5COOH + NaCl we took the aqueous layer extracted from the mixture in the first part and added 70 mL of 10% aqueous hydrochloric acid to acidify it.

A week later once it was dried, we obtained .5002 grams of benzoic acid.

Please show the work of how you found the theoretical yield.

Based on the grinard reagent/reaction (preparation of triphenylmethanol).

4. If you don't oven-dry your glassware or use a drying tube, what byproduct will you produce? Illustate its formation by a chemical reaction.

5. You have air-dried your glassware and used a drying tube during the experiment. However, you used a wet methyl benzoate would the byproduct formed be different from that of question 4 above? Explain your answer.

6. Triphenylmethanol (the final product to be obtained during this experiment) can also be prepared by the reaction of PhMgBr with diethylcarbonate (CH3CH2O)2C=O, followed by H+ workup. Draw the corresponding chemical reaction, and explain your answer.

Question 1:

a. The first four ionization energies of an element are approximately:
738 kJ mol-1, 1450 kJ mol-1, 7.7 x 103 kJ mol-1, and 1.1 x 104 kJ mol-1.
Which family (group) of elements does this element belong? Explain.

b. In a photoelectron spectroscopy experiment the kinetic energy of the ejected electron from
a potassium atom is found to be 5.34 x 10-19 J using a UV source of wavelength 162 nm.
Calculate the ionization energy.

i. It is assumed that this ionization energy corresponds to the valence electron of
potassium in the 4s sublevel. How could you adjust this experiment to be sure that
this is the correct assumption?

1. You are working on a conservation farm with an endangered species of antelope in central Colorado. You notice that birth weight of offspring seems to correlate with air temperature, but that the relationship is not as strong in females as in males. You wonder why that could be.

a) What is your testable hypothesis?

b) Design an experiment to test that hypothesis.

c) What is your null hypothesis?

d) Describe the type of data you will get from the experiment.

e) What type of statistical analysis will you do, and why is it appropriate?

f) Make up some data – at least 10 total. Run your test and show your calculations.

g) What do your results tell you about your hypothesis?

1. write a hypothesis for this chart?

3. Does the data in the table above support your hypothesis for this experiment? Be sure to use

    your data in explaining whether the hypothesis was supported or not.

4. Explain how the tooth length trait was influenced by natural selection in your experiment

Determine if each statement is true or false by dragging labels from below onto the blank fields next to the statements.

The probability of the sample space in every experiment is 100%100%. (TRUE/FALSE)

No event can occur with a chance of 110%110%.   (TRUE/FALSE)

For any two events EE and FF in an experiment, we have P(E∪F)=P(E)+P(F)P(E∪F)=P(E)+P(F).  (TRUE/FALSE)

For every event EE, we have P(E∪Ec)=0P(E∪Ec)=0.   (TRUE/FALSE)

For every event EE, we have P(E∩Ec)=0P(E∩Ec)=0. (TRUE/FALSE)

It contains information on a two factor experiment involving two types of laundry detergent (Super and Best) and three washing temperatures (cold, warm and hot). The numbers given represent the quantity of dirt removed in each wash. Use Excel to conduct a two-factor ANOVA experiment to determine if differences exist in either the type of detergent or the washing temperature. Also determine if differences exist with respect to the interaction of the two factors. Use α = 0.05.

In a physics lab students are conducting an experiment to learn about the heat capacity of different materials. The first group is instructed to add 1.5-g copper pellets at a temperature of 92°C to 345 g of water at 16°C. A second group is given the same number of 1.5-g pellets as the first group, but these are now aluminum pellets. Assume that no heat is lost to or gained from the surroundings for either group.

(a) If the final equilibrium temperature of the copper pellets and water is 25°C, how many whole pellets did the first group use in the experiment? The specific heat of copper is 0.0924 kcal/(kg · °C).

c.) What is the equilibrium temperature of the aluminum and water mixture for the second group? In celsius.