CHEN 3701 Lecture Notes - Lecture 39: Stoichiometry, Cellular Respiration, Respiratory Quotient

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mauvedinosaur421

22 Nov 2015

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7:50 am cell goes to product substrate goes to making product or more cells what other things affect this? temperature if t too high, then quickly plummets arrhenius form for small t range. Chen3701_biomolecularengineering page 1 red: use adaptation to improve tolerance of cells oxygen concentration (po2) also looks like this curve ph. Heat released rate of heat generation (evolution) heat of combustion for biomass heat of combustion of substrate this is complete combustion. Degree of reduction = electron balance ex: methane: glucose: substrate o2 this = alternative balance that can be done. Aerobic degradation of benzoic acid by a mixed culture of different microorganisms can be represented by the following reaction. Determine a through e if respiratory quotient is 0. 9. Determine other yield coeffiients (rq is already coefficients. Determine degreees of reduction for biomass and benzoic acid. C: 7=5c+e --> 5c + e = 7.

Related Questions

1. Write out the balanced equation for the oxidation of hydrobromic acid by hydrogen peroxide.
2. How many stereoisomers of stilbene dibromide can exist?
3. A possible definition of a meso compound is: âwhile possessing 2 or more assignable
stereocenters, a meso compound is superimposable (identical to) its mirror image in at least
one conformationâ. In other words, it is identical to its would-be enantiomer except for the fact
that the molecule containsâ¦ what? What physical characteristic arises in meso compounds
that results in the above definition?
4. Let us assume a cut-and-dry, black-and-white case that the mechanism does only one of 2
things when each molecule of product is produced: (1) goes entirely bromonium-ion/antiaddition;
or (2) goes through a fully-fledged planar carbocation intermediate with absolutely
no selectivity.
a. If you were to find by quantitative analysis that exactly 50% of your product mixture
was the meso stilbene dibromide and the other 50% was racemic stilbene dibromide,
then is mechanism case (1) or (2) favored? If so, qualitatively, by how much?
b. Think again. Question (a) is a mind-bender. I want to know what you originally /
immediately thought, and what you eventually came to. If they are not different, you
are either a genius or need to think more. Write out all the possibilitiesâ¦
c. If you find, qualitatively, that >95% of the product is meso, what does this imply about
the mechanism? What percent of the time does the mechanism go by scenario (1)â¦
greater than what number?
5. Describe a more likely blend of mechanisms that could have produced your estimated product
distribution

periwinklehorse726

Just need help with a few questions from my lab!

Lab Notes:

Experiment 1:

Tube 1: No bubbles produced

Tube 2: Bubbles produced, slowly and sporadically

Tube 3: Bubbles produced, quickly and constantly

Tube 4: Bubbles produced, slowly and sporadically

Tube 5: No bubbles produced

Optimum temp for catalase activity: 40 C

Experiment 2:

Tube 1: 4 min, 42.38 sec

Tube 2: 5 min, 4.37 sec

Tube 3: 5 min, 18.26 sec

Tube 4: 5 min, 28.36 sec

Concentration: 10 mL 3% hydrogen peroxide

Experiment 3:

Tube 1: No bubbles produced

Tube 2: Bubbles produced, quickly

Tube 3: No bubbles produced

Optimum pH for catalase activity: pH 6 buffer

Lab Questions

Experiment 1:

1. Why did catalase fail to function at 80 Â°C?

2. What caused the bubbles to form when you added the catalase to the hydrogen peroxide and water mixture at 40 Â°C?

A. Catalase activity heated the solution to its boiling point.

B. Hydrogen gas formed during the formation of hydrogen peroxide.

C. Oxygen gas formed during the decomposition of hydrogen peroxide.

D. The constant temperature bath heated the solution to its boiling point.

Experiment 2

3. Before the catalase concentration was saturated with hydrogen peroxide, why did the enzyme function vary with substrate concentration?

4. Why did the catalase function level off when different hydrogen peroxide concentrations were tested?

Experiment 3

5. Why did catalase only function in a limited range of pH values?

6. Based on your results from this lab, would you expect the hydrogen peroxide you buy from the store to bubble like soda when you open it?

A. Yes, hydrogen peroxide is only stable in the presence of catalase. Without it, store bought hydrogen peroxide decomposes quickly.

B. No, catalase sped up the rate of the reaction. Store bought hydrogen peroxide will decompose into water and oxygen gas much too slowly for visible bubbles to form.

C .No, hydrogen peroxide can only decompose into water and oxygen gas in the presence of catalase.

D. Yes, catalase had little effect on hydrogen peroxide decomposition. It would bubble quickly no matter what.

7. Do the optimal conditions for catalase functioning that you found correspond with the conditions in the mammalian liver where it came from?

		A. Yes, catalase worked best at a neutral pH and temperature of 40 Â°C, both of which are close to mammalian tissue conditions.
		B. No, catalase functions best at a much higher pH than in mammalian tissue and at a much lower temperature.
		C. Yes, catalase functions best at the same low pH and temperature as occurs in the mammalian tissue.
		D. No, catalase functions best at several very different pHs and temperatures, while the pH and temperature of mammalian tissue does not fluctuate. 8. How much slower would hydrogen peroxide likely be decomposed if catalase was not available in cells? A. 100 times B. 1,000 times C. 10 times D. 1,000,000 times 9. What are the enzyme, substrate, and product in these experiments? 10. What role does catalase play in the mammalian liver, or any other cell it is found in? Thank you!!

For the lab below, what is the separation scheme?

Elimination of 1-octanol.

Apparatus Assembly:

Set up a distillation apparatus.

Using a preweighed 50-mL round-bottom flask as the distilling flask, add 7.5 mL of 1-octanol and weigh it again to determine the exact amount added. Add 2.0 mL of 85% phosphoric acid and 30 drops of concentrated sulfuric acid. Add a magnetic stir bar.

Use a 25 mL round-bottom flask as the receiving flask. Be prepared to immerse it into an ice bath to ensure that no octene vapors will escape into the lab; however, do not add the ice until after the distillation is underway or you will have extra water in your product (from condensation). Even more effectively, you can ice your condenser circulator, but don't do that until after distillation commences either.

Dehydration:

Ensure that the water is flowing in your condenser and begin to heat the distilling flask on the appropriate insert of your heater/stirrer.

The heating should be regulated because ideal time of the distillation should be 30 minutes. Too fast of a distillation will cause an incomplete reaction and isolation of the starting material. The temperature registered by your thermometer will rise very slowly at first, but when the refluxing (soon to be distilling) vapors hit the thermometer, the temperature will rise quickly. It should stabilize as the first condensate begins to form in the distillation condenser; from that point to the end of the distillation, record the range of temperatures: this is your boiling-point range (although in this experiment, the broad distribution of products may cause a broad range of temperatures).

Ideally, you do not want to collect distillate until the temperature is at least 110Â°C (as the distillate, below this temperature, is mostly water); however, since you will have to remove water anyway, this is not critical. However, you don't want to collect product at temperatures much above the boiling point of the octenes since that will increase contamination of your product with unreacted 1-octanol and S_N1 ether byproduct.

Continue the distillation until no more liquid is collected or until tar begins to form; if tar begins to form, stop the distillation. Be sure to not distill the reactants completely, as you will be left with a thick residual tar that will be nearly impossible to remove from the flask.

Isolation and Drying of the Product:

Transfer the distillate to a separate container (flask or separatory funnel) with the aid of an approx. equal quantity of saturated sodium chloride solution (brine). Allow the layers to separate; remove the bottom aqueous layer (using a Pasteur pipet if you chose a flask) and discard it.

Transfer the organic layer (using a dry Pasteur pipet if you chose a flask) in the container to a small round-bottom flask and add a small amount of anhydrous sodium sulfate. Stopper the flask and allow it to sit for 10-15 minutes.

When the product is dry, transfer it to a pre-weighed screw-cap vial (preferably with a Teflon liner) and obtain its mass. Then filter a solution of dichloromethane and product into a GC vial, properly label it, and submit it to the GC vial collection box. The proper ratio of product in dichloromethane is 1 drop in 1-1.2 mL DCM: one drop in a full syringe of DCM.

For this experiment, you will also be required to set up the GC-MS to run your sample by adding your run to the instrument sequence. Follow the instructor's instructions with regard to this task.

CHEN 3701 Lecture Notes - Lecture 39: Stoichiometry, Cellular Respiration, Respiratory Quotient

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