G11 ia design

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G11 ia design

  1. 1. Design of Experiments In Chemistryhttp://www.youtube.com/watch?v= MsVVwfJk6oY&feature=related
  2. 2. Design CriteriaExemplar Report
  3. 3. Design A1Must include : - A research question of the form ‘ what is the effect of changing x on the quantity y ‘ Independent Dependent ControlNotes : All numbers must be associated with units and uncertainty. Significant figures must be consistent. Your choice of variables must be scientifically robust.
  4. 4. Design A2• Method usually of bullet point format.• Must clearly state how the variables identified in 1 are to be controlled and measured.• Write as though you were asking a fellow scientist to repeat the procedure.• Make your control variables realistic.• Have only one dependent and one independent variable.• Include ranges and uncertainties of all glassware, and apparatus.
  5. 5. Design A3• You should always target 5 data points repeated in triplicate.• Your method must have accounted for limiting reagent issues which may preclude you recording relevant data.
  6. 6. • Random errors These arise from the imprecision of measurements and can lead to readings being above or below the “true” value. Random errors can be reduced with the use of more precise measuring equipment or its effect minimized through repeat measurements so that the random errors cancel out. Systematic errors These arise from a problem in the experimental set-up that results in the measured values always deviating from the “true” value in the same direction, that is, always higher or always lower. Examples of causes of systematic error are miscalibration of a measuring device or poor insulation in calorimetry experiments. Accuracy This is how close a measured value is to the correct (literature) value. Precision This indicates how many significant figures there are in a measurement. Human Errors These are due to the incompetence of the operator conducting the experiment and should not be included in your report

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