In this part of today's experiment you will produce cyanotypes using watercolor paper. Directions 1. Each student should obtain a piece of 4” x 5” watercolor paper. Work with ONE partner. 2. Each pair should prepare the following solution in a 250 mL beaker. 1.2g ferric ammonium citrate 0.6g potassium ferricyanide 20 mL of water 3. Stir until dissolved and describe the color of the mixed solution. ______________________ 4. Place the paper in one of the plastic trays under the hood. Using a flat foam brush, coat one side completely with the solution. Wipe first in one direction and then a second time at a right angle to the first direction. 5. CAREFULLY dry the paper using a hot air gun, or place in the oven in the Prep room. 6. When dry, print the dry paper by clipping a large negative image on top of the paper and exposing it to sunlight (outside, if it’s sunny) or a UV light source (inside). 7. When the exposed regions of the paper are changed in color to a deep blue-green, unclip and remove the negative. 8. Wash the paper with a gentle stream of tap water to remove the soluble unreacted light sensitive chemicals. 9. Dry the blueprints with a hot air gun, or in the oven in the Prep room.

Discussion Questions

1. What develops the image?

2. What works as the fixer for the image?

3. Write balanced chemical equations for the reactions observed.

Just as pHpH is the negative logarithm of [H3O+][H3O+], pKapKa is the negative logarithm of KaKa

pKa=−logKapKa=−log⁡Ka

The Henderson-Hasselbalch equation is used to calculate the pHpH of buffer solutions:

pH=pKa+log[base][acid]pH=pKa+log⁡[base][acid]

Notice that the pHpH of a buffer has a value close to the pKapKa of the acid, differing only by the logarithm of the concentration ratio [base]/[acid][base]/[acid]. The Henderson-Hasselbalch equation in terms of pOH and pKbpKb is similar.

pOH=pKb+log[acid][base]

How many grams of dry NH4ClNH4Cl need to be added to 1.80 LL of a 0.100 MM solution of ammonia, NH3NH3, to prepare a buffer solution that has a pHpH of 8.85? KbKb 1.8×10−51.8×10−5.

Express your answer with the appropriate units.

Calculate the theoretical yield of aspirin a) in moles and b) in grams. Assume use of 1.0 g salicylic acid and 2.5 mL acetic anhydride. Show all calculations.

Which plastic types gives identical infrared spectra? Why does this make sense from their structures?

Background info: This is referring to the 6 plastic types: PETE, HDPE, LDPD. PVP, PP ad PS.

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?