MChem Master of Chemistry Environmental Chemistry 2

Question 1

In the context of soil contamination, what does the Koc value measure?

Accepted Answer

The organic carbon-normalized partition coefficient between soil and water

Answer

Koc is the organic carbon-normalized partition coefficient, indicating how strongly a hydrophobic organic pollutant adsorbs to soil organic matter relative to pore water.

Question 2

What is the main mechanism of stratospheric ozone depletion by chlorofluorocarbons (CFCs)?

Accepted Answer

Cl• radicals from photolysis of CFCs catalytically destroy O3

Answer

UV photolysis of CFCs releases Cl• radicals in the stratosphere, which catalytically destroy ozone via Cl• + O3 → ClO + O2 cycles.

Question 3

Which type of chemical weathering converts feldspar minerals in rocks to clay minerals through reaction with carbonic acid?

Accepted Answer

Hydrolysis

Answer

Hydrolysis of feldspars by weakly acidic water (containing dissolved CO2) produces clay minerals (e.g., kaolinite) and releases ions to solution.

Question 4

What is the significance of the octanol-water partition coefficient (Kow) for environmental fate of organic pollutants?

Accepted Answer

It predicts bioaccumulation potential and hydrophobicity

Answer

A high logKow indicates a compound is lipophilic, predicting strong bioaccumulation in fatty tissues and partitioning into organic matter.

Question 5

Which chemical species is primarily responsible for acid rain formation from sulfur dioxide emissions?

Accepted Answer

SO2 is oxidized to SO3 then hydrated to H2SO4

Answer

SO2 is oxidized (in the gas phase by •OH or in droplets by H2O2/O3) to SO3, which reacts with water to form sulfuric acid (H2SO4) — the main acid rain component.

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Environmental Chemistry 2