University:
Felician University
Course:
CHEM-001 | Basic Chemistry
Academic year:

2024
Views:

367

Pages:

13
Author:

Clint W.

ACCURACY & PRECISION WS Idea 1: Measurements (3.25 cm) are different than other numbers (3.14159265). – Measurements represent an action by someone with some measuring instrument. – Measurements have built-in uncertainty; no measurement is exact. – Measurements have units. Idea 2: The uncertainty in a measurement needs to be communicated. Definitions: • accuracy – how close a measurement is to the “true” or accepted value • precision – how close a measurement is to the other measurements Precision versus Accuracy: (Note: it is “accepted” that the bull’s eye is the place everyone aims for.) What is the average density? 18.9/7 = 2.70g/cm3 Subtract the highest value from the lowest value: __2.80-2.60 = 0.20__ Divide this number by 2: 0.10 The precision of the measurement can be shown as 2.70  0.10 g/cm3. Practice Precision (Determine average density, and the precision) Practice Precision Average = 18.9/7 = 2.70 2.80-2.60 = 0.20 Precision is 2.70 + 0.10g/cm3 (happens to be the same precision as previous problem) % Error Calculations %Error = Actual – Experimental X 100 Actual Example Practice % Error Practice % Error Practice Think about it…..

Measurement Notes with Precision and Accuracy Part 4

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