Module 1 - Practical Skills Flashcards
Development of Practical Skills in Chemistry
When is a measurement valid?
When it measures what it is supposed to be measuring.
When is a result accurate?
When it is close to the true value.
What are precise results?
When repeat measurements are consistent/agree closely with each other.
What is repeatability?
How precise repeated measurements are when they are taken by the same person, using the same equipment, under the same conditions.
What is reproducibility?
How precise repeated measurement are when they are taken by different people, using different equipment.
What is the uncertainty of a measurement?
The interval within which the true value is expected to lie.
Define measurement error.
The difference between a measured value and the true value.
What type of error is caused by results varying around the true value in an unpredictable way?
Random error.
What is a systematic error?
A consistent difference between the measured values and true values.
What does zero error mean?
A measuring instrument gives a false reading when the true value should be zero.
Which variable is changed or selected by the investigator?
Independent variable.
What is a dependant variable?
A variable that is measured every time the independent variable is changed.
Define a fair test.
A test in which only the independent variable is allowed to affect the dependent variable.
What are control variables?
Variables that should be kept constant to avoid them affect the dependent variable.
