Last modified on 21 January 2013, at 20:06

A-level Applied Science/Finding out about Substances

About this UnitEdit

From the AQA Specification:

In this unit you will learn about:

  • how to take and prepare samples for analysis;
  • the use of standard procedures to ensure that the results of analysis can be replicated;
  • how to conduct qualitative analysis and a volumetric (quantitative) analysis;
  • how a chromatographic analysis and colorimetric analysis are conducted;
  • how to calculate a molar enthalpy change from experimentation and that energy changes take place during chemical reactions.

How you will be assessedEdit

This unit is assessed through the work you complete for your portfolio.

The marking criteria are found in the AQA specification.

What you need to knowEdit

Qualitative analysis
A-level_Applied_Science/Finding_out_about_substances/Qualitative
Volumetric analysis
A-level_Applied_Science/Finding_out_about_substances/Titration
Chromatography
A-level_Applied_Science/Finding_out_about_substances/Chromatography
Colorimetry
A-level_Applied_Science/Finding_out_about_substances/Colorimetry
Heat of combustion
A-level_Applied_Science/Finding_out_about_substances/Combustion

Scenario 1: Richmond Mine WaterEdit

"The Richmond Mine of the Iron Mountain copper deposit contains some of the most acid mine waters ever reported. Values of pH have been measured as low as −3.6, combined metal concentrations as high as 200 g/liter, and sulfate concentrations as high as 760 g/liter."[1]

Molar concentrations of salts in Richmond Mine water sample.[2]

sample 90WA103
temp 34.8
pH 0.48
Iron(II) 0.323
Aluminium 0.041
Iron (III) 0.020
Magnesium 0.034
Zinc 0.031
Sulphate salts 0.570
Sulphuric acid 0.659

In the investigations which follow, you will examine a sample of water with similar composition to confirm the acid concentration and the ions present. You will use qualitative analysis, titration, colorimetry, chromatography.

ReferencesEdit

  1. Nordstrom, DK and Alpers, CN (1999). Negative pH, efflorescent mineralogy, and consequences for environmental restoration at the Iron Mountain Superfund site, California.. Proc Natl Acad Sci USA.. pp. 3455–3462. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=34288. 
  2. Compositions of five extremely acid mine water samples from the Richmond Mine.