Chemistry Topic: 2 - Experimental Techniques Flashcards
Measurement
What are some factors that require measurement? What apparatus are used for measurement? For each factor, name the apparatus used to measure it as well as the units of measurement.
C2.1
- Factors that require measurement are time, temperature, mass and volume.
- The apparatus used for measurement include burettes, pipettes and measuring cylinders.
- Time is measured using a stopwatch in seconds.
- Temperature is measured using a thermometer in degrees celsius.
- Mass is measured on a mass balance in grams.
- Volume of gas is measured using a Gas syringe in cm³.
C2.1
Criteria of Purity
What is the importance of purity in substances for use in everday life?
C2.2
- Purity is very important in the manufacture of compounds to use in drugs and food additives which are a crucial part of daily life.
- Mixtures melt and boil over a
range of temperatures.
C2.2
Criteria of Purity
What process is used to separate two or more solids that are soluble? How do you calculate Rf values in paper chromatography?
C2.2
- Paper chromatrophy is the process used to separate two or more solids that are soluble.
- To calculate Rf values, the following formula must be used:
- Distance moved by solute / Distance moved by solvent
C2.2
Criteria of Purity
Define a pure substance. Describe three ways the purity of a substance can be assessed.
C2.2
- A substance that contains a single element or compound not mixed with any other substance.
- The 3 ways are:
1. Melting point
2. Boiling point
3. Chromatography
C2.2
Criteria of Purity
Describe how melting point / boiling point can be used to assess purity. Describe how chromatography can be used to assess purity.
C2.2
- A pure substance will have a sharp melting/boiling point. An impure substance will melt over a temperature range.
- A pure substance will produce one well defined spot on a chromatogram.
C2.2
Criteria of Purity
Describe two examples of where purity of substances is important.
C2.2
- Manufacturing of compounds used in drugs and food additives.
C2.2
Methods of Purification
What are some methods of purification?
C2.3
- The methods include separation and purification by the use of a suitable solvent, filtration, crystallisation, distillation, fractional distillation and paper chromatography.
C2.3
Methods of Purification
What is a solvent? What is a solute? What is a solution?
C2.3
- A substance which dissolves a solute is a solvent.
- A substance which is dissolved in a solvent is a solute.
- A liquid mixture composed of two or more substances is a solution.
C2.3
