Lab 1: Measurement

Question 1

What does taring determine?

Answer 1

determines the mass of the weighing container prior to adding the substance to be weighed.

The tare mass is then subtracted from the total mass to determine the actual mass of the substance added.

Question 2

In the bio lab, liquids are commonly measured in _____

Answer 2

L or mL

Question 3

The type of measuring device used in the lab, depends on the degree of ______ and _______ desired and on the size of the volume to be measured.

Answer 3

accuracy, precision

Question 4

Graduated beakers:

Answer 4

give only an approximate measure of volume and should only be used to rough measurement. Their main function is for holding and mixing solutions.

Question 5

Graduated cylinders:

Answer 5

measure variable amounts from 5 to 2000 mL or more. Since the units of calibration vary with the size of the cylinders, the smaller the diameter and total volume, the more accurate and precise the measurements made.

Question 6

Volumetric flasks:

Answer 6

have a single calibration mark and can thus be used to measure only a set volume. Sized range from 5 to 2000 mL or more. They are used in preparing solutions requiring a high degree of accuracy (ex. molar solutions)

Question 7

Pipettes:

Answer 7

used for the accurate measurement of small volumes, come in a range of sizes and types.

Question 8

What are the common types of pipettes?

Answer 8

Mohr, Serological and volumetric

Question 9

What is absorbance?

Answer 9

the amount of light absorbed by a pigment molecules

Question 10

What does the Lambert Beer law describe?

Answer 10

the relationship between absorbance and concentration of pigment molecules in a solution

Question 11

What does the Lambert Beer law state?

Answer 11

for a given concentration range and a sample tube of constant diameter, the absorbance of the solution is directly proportional to the concentration of the pigment molecules.