A surface water sample of 50 ml was taken to determine the concentration of an organic pollutant in the sample. An organic solvent was used as extracting solvent. On analysis of both phases by GC-MS, the pollutant concentration (mass/vol based) in the organic phase was 5 times that found in the aqueous phase. If after the second extraction (each using 50ml fresh organic solvent) the concentration of pollutant in the organic phase was 18 ppm (mass basis), determine the initial mass of pollutant in the water sample before any extractions were carried out. The density of solvent used is 0.65 g/ml & of water is 1.0 g/ml.

Question 1.

An environmental scientist isolates a pollutant (compound X) from a factory’s effluent stream and dissolves it in water. Experiments are then conducted using liquid – liquid extraction to optimize its extraction. Using diethyl ether as the extracting phase, the following distribution ratios, D, are calculated as a function of pH:

1. Does compound X appear to have acidic functional groups, basic functional groups or both types of groups? Explain your answer.
2. The distribution coefficient, K_D, at pH 12 is 76.3. Calculate the K_a value for compound X.
3. The scientist performed multiple extractions of the pollutant from 10 mL of water at pH 6 using a total volume of diethyl ether of 100 mL. What mass of compound X will remain in the aqueous phase after 4 consecutive   extractions if the initial concentration of the pollutant was 0.1 M.

(Note: molar mass of compound X = 76 g/mol)

State the theory and explain how NMR and IR spectroscopy work.

Mass of aspirin: 0.3839

Maximum amount (g) of aspirin possible if salicylic acid is the Limiting Reagent: ?

Maximum amount (g) of aspirin possible if acetic anhydride is the Limiting Reagent: ?

Maximum amount (g) of aspirin possible (the Theoretical Yield): ?

Percent Yield (%) of Aspirin: ?

What are the differences between polyamides and proteins ? I) Polyamides are unable to undergo hydrogen bonding between individual polymer chains. II) Polyamides usually do not have hydroxyl- or thiol-groups as side chains. III) Proteins and polyamides can be partially crystalline. IV) Polyamides have a more stable bond between their monomers than proteins have between the individual amino acids.

Choose one answer.

A. I and II
B. II and III are correct
C. II and IV
D. III and IV

Heavy water, symbolized D2O (D = 2H) finds use as a neutron moderator in nuclear reactors. In a mixture with ordinary water, exchange of isotopes occurs according to the following equation: H2O+D2O⇌2HDO Kc = 3.86 at 298 K. When 1.50 mol of H2O is combined with 1.50 mol of D2O, what are the equilibrium amount of H2O (in moles) at 298 K? Assume the density of the mixture is constant at 1.05 g/cm3.

A scientist measured the properties of a newly synthesized gas molecule. At 55.00 degrees C and 2.090 atm, the specific volume is found to be 0.4947 L/g.

A) Using the ideal gas law, find the molar mass of this molecule.

B) After conducting additional experiments, this scientist measures the critical temperature and pressure of this gas as 308.3 K and 61.4 bar. Was it a good idea in part (A) to assume that the gas was ideal at those conditions?

C) Comparing the physical properties in A and B to known compounds, what molecule do you think this scientist synthesized?

Upon graduation, in a misguided attempt to pay off your student loans more quickly you become involved in the trade of illicit narcotics. Your usual supplier gets eliminated by the competition and you are forced to procure your product from a new supplier. You purchase what your new supplier claims to be codeine (C18H23NO3) of >99% purity but a simple (and ill-advised) taste test leaves you suspicious that it has been thinned with sucrose (C12H22O11). You look up the heat of combustion of codeine (2327 kcal/g) and that of sucrose (2222 kJ/mole). You then take 1.0g of your product and find that it releases 2095 kcal upon combustion. What is the purity of your sample, assuming it contains only codeine and sucrose?

Determine whether each of the following statements is true or false. If the statement is false, modify and rewrite it so that it is a true statement.

a. When a molecule has two, degenerate, “infrared active”, vibrational modes, the two vibrational modes will show absorptions at different frequencies in the infrared spectrum.

b. For a given substance, strong intermolecular forces between molecules of the substance can cause peak broadening of some of the absorptions in the infrared spectrum of the substance.

Bonding is at the heart of chemistry. In chemical reactions, bonds are broken and new bonds are made. Individual atoms break free from their original bonding partners and interact and form bonds with a new bonding partner. All this happens nearly instantaneously. The interaction between the orbitals in two bonding atoms leads to molecular orbitals.

After thoroughly reviewing atomic orbital theory and molecular orbital theory, respond to the following:

• Explain how atomic orbitals interact and give rise to molecular orbitals.

Which of the following set of quantum numbers (ordered n, ℓ, mℓ, ms) are possible for an electron in an atom? Check all that apply.

3, 3, 1, -1/2

4, 2, -2, 1/2

-3, 2, 2, -1/2

3, 1, -2, -1/2

4, 2, -1, -1/2

5, 3, 0, 1/2

4, 2, 3, -1/2

2, 1, 0, 1

What does it mean when we say that a 0.15 M NaCl solution is isotonic with blood, whereas distilled water is hypotonic?

In a calorimeter, we added 50 mL of 1M HCl to 50 mL of 1.1 M NH3 which produces NH4Cl. If the temperature increased 5.0 degrees Celsius, what is the molar enthalpy? We weren't given a heat capacity for the calorimeter but it was made out of a glass beaker and the heat capacity of glass is 0.840 J/g^oC found on google.