Unit 6 EMPA

Question 0

How would you remove impurities from an insoluble solid?

Answer 0

Filter and wash with water.

Question 1

Describe the process of recrystallisation.

Answer 1

1. Dissolve in a minimum amount of solvent.
2. Cool / crystallise.
3. Filter.

Question 2

What is the formula of Tollen’s reagent?

Answer 2

+

[Ag(NH3)2]

Question 3

What is the maximum difference between two concordant results in a titration?

Answer 3

0.10 cm^3

Question 4

To how many decimal places should you record values taken from a burette?

Answer 4

To 2 dp, with the last digit being either 0 or 5.

Question 5

Describe an experiment to determine the melting point of a substance.

Answer 5

Place the substance in a capillary tube and heat it gently.

Question 6

In the observation task, what tells you that there are probably multiple observations you need to make?

Answer 6

“Add x, then add y”

“Then leave to stand for z minutes”

Question 7

What is the method for determining a melting point?

Answer 7

Use melting point apparatus
Heat the substance gently in a melting point tube in an oil bath
Slowly near the melting point