1.2 Liquids and Solutions

Question 1

How do dilutions in linear series differ?

Answer 1

Dilutions in a linear dilution series differ by an equal interval, for example 0·1, 0·2, 0·3 and so on.

Question 2

How do dilutions in log series differ?

Answer 2

Dilutions in a log dilution series differ by a constant proportion, for example 10-1, 10-2, 10-3 and so on.

Question 3

How do you determine an unknown using a standard curve?

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

What effect does the addition of a small amount of acid/ alkali have on a buffer?

Answer 4

Addition of acid or alkali has very small effects on the pH of a buffer

Question 5

Purpose of the addition of a buffer

Answer 5

Allows the pH of a reaction mixture to be kept constant.

Question 6

What must be done to a colorimeter before use?

Answer 6

Calibrate with appropriate blank as a baseline.

Question 7

How do you determine the concentration of a substance using a colorimeter?

Answer 7

Absorbance determines the concentration of a coloured solution using suitable wavelength filters.

Question 8

How do you determine the turbidity of a substance using a colorimeter?

Answer 8

use of percentage transmission, such as cells in suspension.