TOLERANCES OF GRADUATED EQUIPMENT Tolerances are usually larger
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TOLERANCES OF GRADUATED EQUIPMENT Tolerances are usually larger than ± 1 in the last decimal place Tolerances are often provided by the manufacturer 5 -m. L Volumetric Pipet : ± 0. 02 50 -m. L Volumetric Buret : ± 0. 03 100 -m. L Volumetric Flask : ± 0. 08 m. L A tolerance in the hundredths place means the measurement should be given to the hundredths place Reading for a 5 -m. L Volumetric Pipet : Expected range for the measured value : 5. 00 m. L 4. 98 m. L to 5. 02 m. L 5. 00 ± 0. 02 m. L EX 2 -1 (of 11)
READING GRADUATED EQUIPMENT For all measurements, the last digit recorded is an estimated digit EX 2 -2 (of 11)
Most Accurate Graduations: One Celsius Degree Estimated digit: Tenths Reading : 47. 6 Cº EX 2 -3 (of 11)
Most Accurate Graduations: One-Tenth of a Milliliter Estimated digit: Hundredths Reading : 9. 36 m. L 1. 41 m. L EX 2 -4 (of 11)
Most Accurate Graduations: One Milliliter Estimated digit: Tenths Reading : 60. 0 m. L EX 2 -5 (of 11)
Most Accurate Graduations: One Celsius Degree Estimated digit: Tenths Reading : 42. 0 Cº EX 2 -6 (of 11)
Most Accurate Graduations: One Milliliter Estimated digit: Tenths Reading : 81. 5 m. L EX 2 -7 (of 11)
Most Accurate Graduations: One-Tenth of a Milliliter Estimated digit: Hundredths Reading : 24. 16 m. L EX 2 -8 (of 11)
ACCURACY AND PRECISION ERROR – The difference between a measured value and the “true” value of a property ACCURACY – The agreement between a measured value and the “true” value Measured values close to the “true” value are ACCURATE EX 2 -9 (of 11)
ACCURACY AND PRECISION It is rare to know the “true” value of property , but values are “accepted” if they are derived from repeated measurements (density of alcohol at 25°C: 0. 7852 g/m. L) EX 2 -10 (of 11)
ACCURACY AND PRECISION – The agreement among several measured values of the same quantity, and reflects the reproducibility of a given measurement Measured values close to the each other are PRECISE EX 2 -12 (of 11)
