using a large graduated cylinder a student measures out 127ml of a chemical solu
ID: 968839 • Letter: U
Question
using a large graduated cylinder a student measures out 127ml of a chemical solution for an experiment and pours it into a bef Q8. What does the number of significant digits that you report in a labora indicate about the amount of uncertainty in your measurement? t digits that you report in a laboratory measurement Q9. Explai random errors that may have affected the precision of your measurements for this lab. n what is meant by the precision of a measurement. Give some specific examples of Q10. Explain what is meant by the accuracy of a measurement. Give some specific examples of systematic errors that may have affected the accuracy of your measurements for this lab.Explanation / Answer
9 & 10)
Accuracy refers to how close a measurement is to its standard or known value.
Precision refers to how close two or more measurements are to each other, regardless of whether those measurements are accurate or not. It is possible for measurements to be precise but not accurate.
An example of a sensor with BAD accuracy and BAD precision: Suppose a lab refrigerator holds a constant temperature of 38.0 F. A temperature sensor is tested 10 times in the refrigerator. The temperatures from the test yield the temperatures of: 39.4, 38.1, 39.3, 37.5, 38.3, 39.1, 37.1, 37.8, 38.8, and 39.0. This distribution shows no tendency toward a particular value (lack of precision) and does not acceptably match the actual temperature (lack of accuracy).
An example of a sensor with GOOD accuracy and BAD precision: Suppose a lab refrigerator holds a constant temperature of 38.0 F. A temperature sensor is tested 10 times in the refrigerator. The temperatures from the test yield the temperatures of: 37.8, 38.3, 38.1, 38.0, 37.6, 38.2, 38.0, 38.0, 37.4, and 38.3. This distribution shows no impressive tendency toward a particular value (lack of precision) but each value does come close to the actual temperature (high accuracy).
An example of a sensor with BAD accuracy and GOOD precision: Suppose a lab refrigerator holds a constant temperature of 38.0 F. A temperature sensor is tested 10 times in the refrigerator. The temperatures from the test yield the temperatures of: 39.2, 39.3, 39.1, 39.0, 39.1, 39.3, 39.2, 39.1, 39.2, and 39.2. This distribution does show a tendency toward a particular value (high precision) but every measurement is well off from the actual temperature (low accuracy).
An example of a sensor with GOOD accuracy and GOOD precision: Suppose a lab refrigerator holds a constant temperature of 38.0 F. A temperature sensor is tested 10 times in the refrigerator. The temperatures from the test yield the temperatures of: 38.0, 38.0, 37.8, 38.1, 38.0, 37.9, 38.0, 38.2, 38.0, and 37.9. This distribution does show a tendency toward a particular value (high precision) and is very near the actual temperature each time (high accuracy).
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