Environmental Chemistry Written Assignment

Assessment Task 1

Term 1 – Environmental Chemistry

Assessment

 task

 1—

 Written

 assessment

Weighting:

 25%

Objectives

This assessment task requires some research (i.e. you need to consult

references outside of the textbook; however do not limit yourself to the

Internet). It is important to start on this assessment task as early as

possible. Remember to always cite your sources throughout your

report.

Part

 1

 (20

 %)

(a) Summarise in a single concise table the typical composition (i.e.

typical ions and their concentrations) of rivers, groundwaters and

seawaters. Compare the typical levels found and note down some

significant observations.

(b) Compare the typical composition (i.e. chemical species present

and typical concentration levels) of domestic wastewaters and of

sewage sludge. Comment on any similarities and differences in their

composition.

(c) Look up the ANZECC & ARMCANZ (2000) water quality guidelines

and summarise the relevant criteria for the species listed in (a).

Assessment Task 1

Term 1 – Environmental Chemistry

Part

 2

 (25

 %)

The major component of natural gas used by utility companies is

methane, CH4; the gas used in gas barbecues is propane, C3H8.

Assuming that each gas burns completely, compare the amount of

energy released by each gas:

(a) in terms of kJ/mol of CO2 produced, and

(b) in terms of kJ/g of fuel.

Do the calculations based on chemical bonds broken and formed in

the combustion reactions. Below are some useful average bond

dissociation energies (source: Spiro & Stigliani 2003):

Bond Enthalpy (kJ/mol)

C-C - 347

C-H - 410

C=O - 799

O-H - 460

O=O - 494

Part

 4

 (20

 %)

Give two examples each of natural and anthropogenically-generated

greenhouse gases. For each example, discuss some of its specific

environmental impacts and any proposed or existing management or

control actions.

Assessment Task 1...