C7.5 Analytical procedures

Question 1

1. What is a QUALITATIVE method of analysis?

Answer 1

• tells you which substances in the sample

- doesn’t tell you how much of substance

Question 2

1. What is a QUANTITATIVE method of analysis?

Answer 2

• tells you how much of a substance in sample

- can work our molecular formula of sample (e.g. what type of hydrocarbon is made from hydrogen and carbon)

Question 3

2. How are chemical analyses carried out?

Answer 3

-an analysis must be carried out on a sample that represents the bulk of the material under test

Question 4

2. Why are chemical analyses carried out on samples?

Answer 4

• difficult to test all the material
• can correct if something goes wrong
• represents bulk of material

Question 5

3. What are many analytical methods based on?

Answer 5

-samples in solution

Question 6

3. How is a solution made?

Answer 6

-by dissolving the sample in a solvent

Question 7

3. What types of solutions are there?

Answer 7

• aqueous: sample dissolved in water

- non-aqueous: sample dissolved in other solvent, e.g. ethanol

Question 8

4. What are standard procedures?

Answer 8

-clear instructions to describe exactly how to carry out practical tasks

Question 9

4. What are examples of what can have standard procedures?

Answer 9

-the collection, storage and preparation of samples for analysis

Question 10

4. How are standard methods chosen?

Answer 10

• safest, most effective, accurate methods

- in a company, nationally, internationally

Question 11

4. Why are standard procedures useful?

Answer 11

-result should be the same and reliable every time