What are NHCs and how do they differ from "normal" carbenes?(NHCs is N-heterocyclic carbenes)
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For a particular redox reaction NO is oxidized to NO3
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How does NMR allow us to understand the connection between bond rotation and the kinetic energy within the sample being analyzed?
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At 1 atm, how much energy is required to heat 37.0 g of H2O(s) at –10.0 °C to H2O(g) at 169.0 °C? Helpful constants can be found here.
| Quantity | per gram | per mole |
| Enthalpy of fusion | 333.6 J/g | 6010. J/mol |
| Enthalpy of vaporization | 2257 J/g | 40660 J/mol |
| Specific heat of solid H2O (ice) | 2.087 J/(g·°C) * | 37.60 J/(mol·°C) * |
| Specific heat of liquid H2O (water) | 4.184 J/(g·°C) * | 75.37 J/(mol·°C) * |
| Specific heat of gaseous H2O (steam) | 2.000 J/(g·°C) * | 36.03 J/(mol·°C) * |
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If your favorite silver jewelry ever tarnishes and you happen to have some aluminum foil on hand, you can actually get rid of some of that tarnish. The tarnish here is actually silver sulfide. If you put the jewelry and aluminum into a dish with enough water to cover them both, the following reaction will occur: 3Ag2S + 2Al --> 6Ag + Al2S3. If you have a total of 5.0 g of Al foil accessible to you, how many grams of Ag2S (thus, loosely speaking, how much jewelry) could you theoretically "clean"? You must show all work clearly and in detail to receive credit. All numbers immediately following elemental symbols should be understood as subscripts. (NOTE: If you try this at home, you may want to dissolve some baking soda in your solution to help neutralize the smell, because some of the sulfur here will escape as a gaseous product and not smell very pleasant!)
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A buffer solution is prepared by mixing 20.0 mL 0.45 M HAc (acetic acid) with 35.0 mL 0.45 MNaAc (sodium acetate) (a) What is the amount of 4.0 M HAc which must be added to this buffer solution to double [H3O+]? (b) What is the amount of 2.0 M HCl that must be added to decrease the pH by 0.50? (c) How much NaOH(s) in g has to be added to the solution to raise the pH by 2.00?
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I made a solution of fluorscein and diluted it with ethanol, and I was confused about some stuff.
Does emission and excitation depend on concentration?
Would would change if I diluted it with water rather than ethanol?
What is stoke's shift and what is an anti - stoke?
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The following compounds can be formed during the Maillard reaction. For each compound:
|
Compound |
From Caramelization? (Y/N) |
Color |
Aroma/Taste |
#O’s |
#N’s |
#S’s |
Ring Y/N |
C=O Y/N |
|
Diacetyl |
||||||||
|
2,4,5-trimethyl thiazole |
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|
2-acetyl-3,5-dimethyl pyrazine |
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|
Difurfuryl sulfide |
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|
3-ethyl pyridine |
||||||||
|
Furfural |
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|
Levulinic acid |
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|
1-methyl pyrrole |
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|
Phenylpyruvic acid |
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|
2-thienyl mercaptan |
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Explain anaplerortic reactions and describe the principal such reaction for the CAC and the regulation of its activity in animals
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at 25 C, a 0.010mol/L ammonia solution is 4.3 percent ionized. Calculate the pH
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Suggest some possibilities as to why your buffer pH might not be exactly 8.0
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4. If you expect the unknown acid molarities to be between 0.010 M and 0.20 M and the sodium hydroxide solution to be 0.050 M, what volume of unknown acid solution would you place into the flask? State your reasoning or assumptions that you make (perhaps typical of those given in question 3, perhaps not) and show your calculation.
Bonus. State two possible errors when using burets that would reduce the accuracy of your titration. Explain specifically whether the result would be a calculated acid molarity that is smaller than the actual value or a calculated acid molarity that is larger than the actual value.
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Briefly discuss the chemistry of the aqua complexes of [Mo3Q4(H2O)9] 4+ (where Q = S or Se).
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For the following reaction, Keq is 0.00183 at 390. K: PCl5(g) PCl3(g) + Cl2(g) If 2.89 g of PCl5 is placed in a 2.86 L bulb at 390. K, what is the equilibrium pressure of Cl2? 1 atm = 1.013 bar
answer in bar
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3) The following “cycle of copper” experiment is performed in some general chemistry laboratories. The series of reactions starts with copper wire and ends with metallic copper. The steps are as follows:
I. A piece of copper wire of known mass is allowed to react with concentrated nitric acid, the products are copper(II) nitrate , nitrogen dioxide, and water.
II. The copper(II) nitrate is treated with a sodium hydroxide solution to form copper(II) hydroxide.
III. On heating, the copper(II) hydroxide decomposes to yield copper(II) oxide.
IV. The copper(II) oxide is combined with concentrated sulfuric acid to yield copper(II) sulfate.
V. Copper(II) sulfate is treated with excess solid zinc metal to form metallic copper.
VI. The remaining zinc metal is treated with hydrochloric acid, and metallic copper is filtered, dried, and weighed.
a. Write a balanced chemical equation for each step. Be sure to pay attention to phase labels.
b. Classify each reaction as a precipitation, acid-base, or redox reaction.
c. Assuming that a student started with 65.6 g of copper, calculate the theoretical yield for each step
In: Chemistry