A 1.0 L buffer solution is made up of 0.15M NaF and 0.20 M HF ( pK a = 3.17) . 0.05 mol of HCl is added to it. What is the new pH?

Please calculate the pH of each of the following solutions: 0.68 M NaCH3CO2 (aq); 0.45 M KCN (aq).

25 ml of 0.105 M HCl is titrated with 0.210 M NaOH

a. What is the ph after 5 ml of the base is added?

b. what is the ph at the equivalence point?

c. What is the ph after 15 ml of the base added?

d. how many ml of the base will be required to reach the end point?

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)