MChem Master of Chemistry Environmental Chemistry

Question 1

What is the primary chemical reaction responsible for the formation of tropospheric ozone in urban smog?

Accepted Answer

Photolysis of NO2 followed by O + O2 → O3

Answer

Tropospheric ozone forms when UV light photolyzes NO2 to produce atomic oxygen, which then combines with O2 to form O3.

Question 2

Which greenhouse gas has the highest global warming potential (GWP) on a per-molecule basis over a 100-year horizon?

Accepted Answer

Sulfur hexafluoride (SF6)

Answer

SF6 has a GWP of approximately 23,500 over 100 years, making it the most potent greenhouse gas regulated under the Kyoto Protocol.

Question 3

What chemical process converts dissolved CO2 in the ocean to carbonic acid, contributing to ocean acidification?

Accepted Answer

CO2 + H2O → H2CO3

Answer

CO2 dissolves in seawater and reacts with water to form carbonic acid (H2CO3), which dissociates to lower ocean pH.

Question 4

What is the Henry's Law constant used to describe in environmental chemistry?

Accepted Answer

The equilibrium partitioning of a chemical between air and water

Answer

Henry's Law constant (KH) describes the ratio of a chemical's concentration in the gas phase to its concentration in aqueous solution at equilibrium.

Question 5

Which process describes the increase in concentration of persistent pollutants (e.g., PCBs) at higher trophic levels in a food chain?

Accepted Answer

Biomagnification

Answer

Biomagnification is the progressive increase in concentration of lipophilic, persistent pollutants as they move up the food chain from prey to predator.

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Environmental Chemistry