PART A: Choose the bond below that is least polar

A. C-F

B. C-Cl

C. C-Br

D. C-I

E. C-O

Please explain how the answer is found

PART B: Which of the following molecules is polar?

A. CO₂

B. CCl₄

C. H₂

D. NO₂

E. O₃

Please explain your answer

PART C: Which of the following polyatomic ions is polar?

A. NH₄⁺

B. OH^-

C. SO₄^-

D. PO₄^3-

Please explain your answer

The weak acid HA with a dissociation constant Ka is distributed between and organic solvent and water. If the only extractable species is the undissociated species HA with a partition coefficient K, derive an expression showing the dependence of the distribution ratio, D, on [H+] of the aqueous phase and draw conclusions from this expression.

For an element X, the following standard reduction potentials exist at a temperature of our study:

X^3+(aq) + 2 e– → X^+(aq) ε1° = 1.192 V

X^4+(aq) + 3 e– → X^+(aq) ε2° = 1.241 V

If [X^+] = 0.170 M, [X^3+] = 5.670 M, and [X^4+] = 0.174 M, at what temperature (in °C) will the galvanic/voltaic cell made from the above two half-reactions begins to become nonspontaneous?

Part B How many grams of dry NH4Cl need to be added to 2.40 L of a 0.800 M solution of ammonia, NH3, to prepare a buffer solution that has a pH of 8.66? Kb for ammonia is 1.8×10−5. Express your answer with the appropriate units.

Given the following reaction, which is the formation of an iron oxide mineral via hydrolysis:

Fe3+ +3H2O = Fe(OH)3(s) + 3H+

1) Identify the Lewis acids and bases in the above reaction.

2) Define Le Chatelier's principle.

3) Explain how Le Chatelier's principle can be applied to the above reaction. Specifically, how would increasing the pH of the reaction change the relative amount of Fe3+ vs Fe(OH)3?

i believe i understand sigma and pi for covalent bonds... however do not understand sigma and pi bonds for ionic bonds. so   what are properties of ionic sigma pi bonds...can you/we sketch them. what makes them different from convalent sigma pi bonds?   TY

Consider two compounds for which t_m = 1 min, t₁ = 14.3 min and t₂ = 15.0 min. The peak widths at half heights are 13.0 sec and 14.9 sec, respectively. What are the peak widths? (This requires that you think about the mathematics of a Gaussian curve.) Calculate the resolution of this separation. How many theoretical plates does the column have for these analytes? What is the value of the selectivity factor, α?

given the reaction: Reaction of Dimedone and Benzaldehyde (2 Part)

overview Part 1:

Using a Pasteur pipet, add 0.2 g of benzaldehyde to 50 mL Erlenmeyer flask. 2. Add 8 mL of 1:1 ethanol/water and swirl the flask to mix the content. 3. Add 0.6 g of dimedone and 3 drops of piperidine, and 2-3 boiling chips 4. Boil gently for 5 min on a hot plate 6. at the end of 5 minutes let the mixture cool, followed by cooling in an ice bath to complete crystallization5. Collect crystals by vacuum filtration, washing with several 10 mL portions of ice cold 1:1 ethanol: water, Gently break the crystals with a spatula and let them sit on the vacuum for 30 min to dry.

overview Part 2:

Next if 250mg of product (from above) and 10 ml of absoulte enthanol were put into an erenmeyer flask, heated. Then 2.5ml of water and 6 drops of 6M HCL were added. The mixture was left to to continue  boiling. the flask was removed fro heat and water was added dropwise until the mixture becomes cloudy. The product is collected.

Questions:

1. why is it possible for dimedone to have two tauromers?

2. what spectroscopy methods can you use to prove the formation of tautomers?

3. why do you use piperdine during the first step of this reaction? could you use inorganic base instead?

4. what are the differences in IR between benzaldehyde and the product from part 2 (3,3,6,6-tetramethyl-9-phenyl-3,4,5,6,7,9-hexahydro-1h-xanthene-1,8(2h)-dione)

1. Which of the following buffers would be the best choice for a desired pH of 3.0:

            a. Acetic acid (pKa=4.74)

            b. HF (pKa= 3.14)

            c. Carbonic acid (pKa=6.37)

            d. Propanoic acid (pKa=4.85)

            e. Not enough information is given

2. A buffer (1L total volume) contains 0.15 moles ammonia and 0.25 moles ammonium chloride (pKa=9.26). What is the pH of that buffer solution? What is the pH after 0.0025 moles of KOH are added?

3. Which of the following makes the best buffer (assume equal volumes):

1. 0.1 M HNO₃ and 0.1 M LiOH
2. 0.1 M acetic acid (K_a = 1.8E-5) and 0.1 M NaOH
3. 1M acetic acid (K_a = 1.8E-5) and 0.0001 M sodium acetate
4. 0.1 M acetic acid and 0.1 M sodium acetate

4. When adding strong base to a buffer, which component of the solution is reacting with that strong base? Draw the reaction using HA for the weak acid and A- for the weak base.

Hi, would appreciate some answers and explanations to the below. If you have any sources to back up any points would be amazing but not necessary, Thanks!

1) Why is dichloromethane used to extract the clove oil from the distillate? (In reference to the extraction of eugenol from cloves via steam distillation).

2) Discuss the advantages of using dichloromethane compared to other organic solvents such as hexane, benzene, or diethyl ether?

3) What are some of the potential disadvantages of using dichloromethane as a solvent?

- Neon Emission Spectrum

A. Based on the emission spectrum for neon, what color would you predict for the neon tube? ______________________________

B. Search on Google for an image photo of a neon spectrum tube. Was your prediction correct? ____________________________

C.What is responsible for the color of a neon discharge tube?_________________________________________________________

- Sodium Emission Spectrum

A. The most prominent line in the emission spectrum of sodium is the result of a transition from a 3p to a 3s orbital. The wavelength of this line is 5893 Å. Convert this to nanometers (show your calculation) and give the color of light corresponding to this wavelength.

B. Based only on the color of the lines corresponding to the transitions, is the sodium 3p  3s transition of higher or lower energy than the n=3  n=2 transition in the hydrogen atom? Explain.

Predict a likely mode of decay for each of the following unstable nuclides. EXPLAIN why this might be so. a) Mo-109 b) Fr- 202 c) Rn- 196 d) Sb - 132 e) P - 27 f) Ru - 90

Assuming that no equilibria other than dissolution are involved, calculate the concentrations of ions in a saturated solution of each of the following (see Appendix J for solubility products).

(a) TlCl

(b) BaF2

(c) Ag2CrO4

(d) CaC2O4·H2O

(e) the mineral anglesite, PbSO4

Combustion analysis of a 13.42-g sample of the unknown organic compound (which contains only carbon, hydrogen, and oxygen) produced 36.86g CO2 and 10.06g H2O. The molar mass of estriol is 288.38g/mol .

Find the molecular formula of the unknown compound