CIA Demonstration: Precision and Accuracy with Glassware (1.3.3)

Question 1

• There are many types of glassware for measuring volume in the laboratory.

Answer 1

• There are many types of glassware for measuring volume in the laboratory.

Question 2

• Precision is the ability to reproduce a measurement, while accuracy is how close the measurement is to the true answer.

Answer 2

• Precision is the ability to reproduce a measurement, while accuracy is how close the measurement is to the true answer.

Question 3

• A pipet is more precise because of its small cross-section at the meniscus.

Answer 3

• A pipet is more precise because of its small cross-section at the meniscus.

Question 4

There are many types of glassware for measuring
volume in the laboratory.

Volumetric pipets and graduated cylinders are
two examples of laboratory glassware.

Volumetric pipets are used to deliver specific fixed
volumes of liquids. For example, some volumetric
pipets are calibrated to deliver 50.00 mL of liquid,
while others are calibrated to deliver 5.00 mL of
liquid.

Graduated cylinders are used to measure variable
volumes of liquid. For example, a 50 mL graduated
cylinder could be used to deliver any volume
between 0.0 mL and 50.0 mL, such as 38.3 mL.

Answer 4

There are many types of glassware for measuring
volume in the laboratory.

Volumetric pipets and graduated cylinders are
two examples of laboratory glassware.

Volumetric pipets are used to deliver specific fixed
volumes of liquids. For example, some volumetric
pipets are calibrated to deliver 50.00 mL of liquid,
while others are calibrated to deliver 5.00 mL of
liquid.

Graduated cylinders are used to measure variable
volumes of liquid. For example, a 50 mL graduated
cylinder could be used to deliver any volume
between 0.0 mL and 50.0 mL, such as 38.3 mL.

Question 5

Precision is the ability to reproduce a measurement,
while accuracy is how close the measurement is to
the true answer. For example, If the goal is to hit
the bull’s eye, the three throws on the left are
precise, but not accurate. The throw on the right is
accurate.

Different pieces of glassware have different degrees
of precision and accuracy associated with them.

Answer 5

Precision is the ability to reproduce a measurement,
while accuracy is how close the measurement is to
the true answer. For example, If the goal is to hit
the bull’s eye, the three throws on the left are
precise, but not accurate. The throw on the right is
accurate.

Different pieces of glassware have different degrees
of precision and accuracy associated with them.

Question 6

The volume of water delivered by a piece of
glassware can be calculated from the mass of water
delivered and the density of water at a specific
temperature.

The average volume of water delivered is 49.87 mL
for both pieces of glassware. Therefore, the two
pieces of glassware are equally accurate.

However, the standard deviation of the volume
delivered by the volumetric pipet is smaller.
Therefore, the volumetric pipet is more precise than
the graduated cylinder. A pipet is more precise
because of its small cross-section at the meniscus.

Answer 6

The volume of water delivered by a piece of
glassware can be calculated from the mass of water
delivered and the density of water at a specific
temperature.

The average volume of water delivered is 49.87 mL
for both pieces of glassware. Therefore, the two
pieces of glassware are equally accurate.

However, the standard deviation of the volume
delivered by the volumetric pipet is smaller.
Therefore, the volumetric pipet is more precise than
the graduated cylinder. A pipet is more precise
because of its small cross-section at the meniscus.