Note:

IGCSE Topic Questions for  Experimental Techniques Paper 4  Extended Theory

Syllabus Objectives:

2.1 Measurement 

CORE:

• Name appropriate apparatus for the measurement of time, temperature, mass and volume, including burettes, pipettes and measuring cylinders

2.2 Purity

2.2.1 Criteria of purity

Core

• Demonstrate knowledge and understanding of paper chromatography 
• Interpret simple chromatograms 
• Identify substances and assess their purity from melting point and boiling point information 
• Understand the importance of purity in substances in everyday life, e.g. foodstuffs and drugs Supplement 
• Interpret simple chromatograms, including the use of Rf values 
• Outline how chromatography techniques can be applied to colourless substances by exposing chromatograms to substances called locating agents. (Knowledge of specific locating agents is not required.)

2.2.2 Methods of purification

Core 

• Describe and explain methods of purification by the use of a suitable solvent, filtration, crystallization and distillation (including use of a fractionating column). (Refer to the fractional distillation of petroleum in section 14.2 and products of fermentation in section 14.6.) 
• Suggest suitable purification techniques, given information about the substances involved