Chemistry Practical Key Terms 0.0 / 5 ? ChemistryPracticalA2/A-levelAQA Created by: keira.graceCreated on: 29-06-21 13:03 When is a measurment valid? When it measures what it is supposed to be measuring. 1 of 14 When is a result accurate? When it is close to the true value. 2 of 14 What are precise results? When repeated measurements are consistent with eachother. 3 of 14 What is repeatability? How precise repeated measurements are when they are taken by the same person, using the same equipment and by the same conditions. 4 of 14 What is reproducibility? How precise repeated measurements are when they are taken by different people, using different equiptment. 5 of 14 What is uncertainty of a measurement? The interval within which the true value is expected true value. 6 of 14 Define measurement error. The difference between a measurement value and the true value. 7 of 14 What type of error is caused by results varying around the true value in an unpredictable way? A random error. 8 of 14 What is a systematic error? A consistent difference between the measured values and true values. 9 of 14 What does zero error mean? A measuring instrument gives a false reading when the true value should be zero. 10 of 14 Which variable is changed or selected by the investigator? Independent variable. 11 of 14 What is a dependent variable? A variable that is measured every time the independent variable is changed. 12 of 14 Define a fair test? A test in which only the independent variable is allowed to affect the dependent variable. 13 of 14 What are control variables? Variables that should be kept constant to avoid them affecting the dependent variable. 14 of 14
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