Liquids and solutions

Question 1

How do dilutions in a linear dilution series differ?

Answer 1

By an equal interval eg. 0.1, 0.2, 0.3

Question 2

How do dilutions in a log dilution series differ?

Answer 2

By a constant proportion e.g 10-1, 10-2, 10-3

Question 3

What does the production of a standard curve allow?

Answer 3

Plotting measured values for known concentrations to produce a line or curve allows the concentration of an unknown to be determined from the standard curve.

Question 4

How do buffers control the pH of a solution?

Answer 4

Addition of acid or alkali has very small effects on the pH of a buffer, allowing the pH of a reaction mixture to be kept constant.

Question 5

When using a colorimeter what has to happen?

Answer 5

Calibration with an appropriate blank to act as a base line for comparison.

Question 6

Using a colorimeter what can absorbance be used to determine?

Answer 6

Absorbance can be used to determine the concentration of a coloured solution using a suitable wavelength filter.

Question 7

Using a colorimeter what can percentage transmission be used to determine?

Answer 7

Percentage transmission can be used to determine turbidity, such as cells in suspensions.