Physical and Inorganic Chemistry Assignment

Part A

NSCI*172: Covid-19 Myths and Vaccines

  1. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/myth-busters .  Select 3 of your favorite myths from the website and state in 2-3 sentences (for each) why it is not true.
  2. https://www.cnn.com/2020/06/08/health/covid-19-vaccine-latest/index.html and answer these questions.

Part B

CHEM11042 Fundamentals of Chemistry

In completing this assessment:

Question 1                                                                                               (30 marks)

In the Haber process, ammonia is produced from an exothermic reaction of nitrogen and hydrogen, in the presence of a catalyst, according to the following reaction:

N2(g) + 3H2 (g)          2NH3(g)

  1. and explain the effect on equilibrium for this reaction, due to the following:

3 NaHCO3 (aq) + C6H8O7 (aq)          3 CO2 (g) + 3 H2O (l) + Na3C6H5O7 (aq)

Following some experimental testing, two blends have been proposed for the tablet composition, namely:

Blend 1:   6.00 gram of NaHCO3 mixed with 6.00 gram of C6H8O7 Blend 2:      6.00 gram of NaHCO3 mixed with 2.00 gram of C6H8O7

Question 2 (20 marks)
  1. 9H8O4, as the active ingredient.

Calculate the concentration of the solution prepared following the complete dissolution of 4 tablets in 500.0 mL of water. Express this concentration in

(2 marks)

Question 3 (10 marks)

half-life of 68.9 years. Will a sample of Uranium-232 be at less than one tenth 10 of its

original strength after a period of 200 years?  Explain.                       (4 marks)

Question 4                                                                                                (15 marks)

(2 marks)

HF       +     H O       F−          +      H O+

(aq)          2    (l)             (aq)            3      (aq)

calculate the pH of this buffer.                                                       (4 marks)

  1. What will the pH of the buffer be following a 10 dilution?

Explain your answer.                                                                    (2 marks)

  1. How will the buffer capacity of the buffer be affected following a 10 dilution?

Explain your answer.                                                                    (2 marks)

Question 5 (25 marks)

OH CH3CH2CHCH2CH2CH3

(2 marks)

(3 marks)

CH3 CH3CH2NCHCH2CH2CH3

CH3

OH      CH2CH3

Part C

NSCI172:  Science & Society - trans fats

Purpose: Learn about trans fats and address the role of governments in regulation of food

Resources: textbook and https://www.cdc.gov/nutrition/downloads/trans_fat_final.pdf

Beginning in 2006, the Food and Drug Administration (FDA) required all nutrition labels to list the amount of trans fat in the food. It is permissible for a nutrition label to indicate “zero” trans-fat if the amount is 0.5 g or less. This is an example when significant figures and rounding play a role! After the FDA regulation, certain cities and states began to ban the use of trans fats in restaurants. In 2015, the FDA announced that it will implement a total ban on trans fats within a three-year period.

Please answer these 6 questions. Be sure to answer all parts of each question in complete sentences.

Part D

SECTION A

This section contains 2 questions, 20 marks each.

Question 1. Write an essay about HPLC (maximum 3 pages). 20 marks The essay should include discussion about basic principles, basic components of a HPLC instrument, limitations, methods, gradient elution, application fields, etc.

Question 2. Write an essay about IR spectroscopy (maximum 3 pages). 20 marks The essay should include discussion about basic principles, basic components of an IR instrument, type of IR instruments, working principle, measurement techniques, application fields, etc.

SECTION B

This section contains 6 questions, 10 marks each.

Question 3. 5 + 5 marks

(a) Consider two compounds (1 and 2) for which the void time tM= 1 min, and retention times t1= 11.30 min and t2=12 min. The peak widths at half-height are 10 s and 12 s, respectively. Calculate the time the analytes spend in the stationary phase. Calculate the column resolution.

(b) The chromium (52 g/mol) content of a polluted sample was measured using UV-Vis spectroscopy based on the absorption of its diphenyl carbazide complex at 540 nm. The absorbance of the sample was 0.41. A reference sample containing 2 ppm chromium had absorbance of 0.93. The optical path length of the cell was 1 cm. Calculate the concentration of chromium in the polluted sample and the molar absorptivity of the complex at 540 nm.

Question 4. 5 + 5 marks

(a) Explain the working principle of a flame ionization detector (FID) in GC. Name advantages and disadvantages of FID. Sketch a neat labeled picture of FID.

(b) The phosphate concentration in a solution was determined based on the absorption of the yellow complex of phosphate and ammonium vanadomolybdate. Measurements were done at 415 nm using a glass cell of 1 cm path length. A series of standard solution was prepared, and the unknown solution was pretreated the same way. The unknown solution gave an absorbance of 0.41, and those of standard solutions are listed below. Determine the phosphate concentration in the unknown solution. Produce a calibration curve from the measured data, and derive an equation relating absorbance to phosphate concentration. Solutions Concentration (mmol/L) Absorbance 1 2 3 4 5 6 0.0 0.05 0.15 0.25 0.35 0.45 0 0.07 0.21 0.35 0.48 0.62

Question 5. 6 + 4 marks

(a) Three isomers share the same formula, C2HCl3F2. Draw the structure of these isomers. Is it possible to distinguish between these isomers on the basis of their 1H NMR spectrum? Justify your answer by predicting the 1H NMR spectra (sketch spectra, consider spin-spin coupling, consider relative chemical shifts).

(b) What does the “C-18 silica” reversed phase column mean. Explain. In what order would the following compounds be eluted from a C-18 reverse phase column using 1:1 acetonitrile: water as the eluting solvent? Justify jour answer. 1. CH3COCH3 (acetone), 2. C6H5CH3 (toluene), 3. C6H4(OH)COOH (salicylic acid)

Question 6. 6 + 4 marks

(a) A standard 2 ppm solution of an analyte gave a signal reading of 0.16 using an instrument. In order to determine the detection limit, a series of sequential base line measurements were performed using a blank solution. The signal readings were 0.004 0.002, 0.007, 0.006, and 0.003. Calculate the detection limit. Provide a definition for the detection limit.

(b) How many groups of signals do you expect in the 1H NMR spectrum of isopropanol, CH3CH(OH)CH3? And how many signals do you obtain if you consider spin-spin coupling? Sketch the spectrum. Explain. Predict the proton decoupled 13C NMR spectrum of the molecule.

Question 7. 5 + 5 marks

(a) Explain the working principle of the historic Pregl apparatus (CH analyzer).

(b) The potassium concentration in an aqueous sample is analyzed using the method of addition and flame emission. Two 0.5 mL portions of the unknown sample were taken to create two identical solutions. 20 µL of 0.1 M aq. KCl solution is added to one of these. Then, both solutions were diluted further with distilled water to a final volume of 5 mL. The values obtained from the apparatus were 38.0 and 61.0 arbitrary units. What is the potassium concentration of the aqueous sample?

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