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Chemistry Lecture L.S. 1. Measurement. Measurement. Measurement is an important concept in any lab based science class. Measurements should be taken with care and reflect the uncertainty associated with them.
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Chemistry Lecture L.S. 1 Measurement
Measurement • Measurement is an important concept in any lab based science class. • Measurements should be taken with care and reflect the uncertainty associated with them. • Measuring with uncertainty means that you recognize that there is an element of estimation to your measurement and account for it when recording.
Measurement • If you are using a triple beam balance which only measures to the 0.1g (like ours at KLHS), then any recorded measure past that point is estimation. • Suppose one student measures the mass of an object to be 52.34g, another measures the mass to be 52.33g, and yet another believes it to be 52.35g. Because the last digit of all 3 measurements is clearly an estimation of the part of the measurer, the measurement should be recorded as 52.33 0.01g. This is an honest measurement that shows the last digit was estimated.
Measurement Questions about measuring with uncertainty?
Accuracy is the closeness of a measured quantity to its true or accepted value. Precision is the degree of agreement among several measurements. Measurement
Measurement • In the first target, they are both accurate and precise. • In the second target, they are precise, but not accurate. • In the third target, they are not precise, but there are a few accurate shots.
Measurement Questions about precision and accuracy?
Measurement • A couple of other units of measure will also be used in this class. • Temperature: Celsius (°C) • Pressure: atmospheres (atm) • Pressure: millimeters of mercury (mmHg) • Mass: atomic mass units (amu)
Measurement Any final questions?