Chemical Analysis

Question 1

What is the purpose of testing substances in chemistry?

Answer 1

To find out if they contain specific ions or compounds.

Question 2

What are the two methods to test for metal cations?

Answer 2

• Flame tests
• Precipitate tests

Question 3

What is the principle behind flame tests for metal cations?

Answer 3

Most metal ions produce a strong colour when put into a blue Bunsen burner flame.

Question 4

What is the first step in conducting a flame test?

Answer 4

Make a small loop in the end of a clean nichrome wire.

Question 5

What should be done with the nichrome wire before conducting a flame test?

Answer 5

Dip the loop into concentrated hydrochloric acid and then into the sample.

Question 6

What should you do after dipping the wire into the sample for a flame test?

Answer 6

Hold the loop in a blue Bunsen flame and record the first colour you observe.

Question 7

What colour flame does lithium (Li+) produce in a flame test?

Answer 7

Crimson

Question 8

What colour flame does sodium (Na+) produce in a flame test?

Answer 8

Yellow / orange

Question 9

What colour flame does potassium (K+) produce in a flame test?

Answer 9

Lilac

Question 10

What colour flame does calcium (Ca2+) produce in a flame test?

Answer 10

Brick red

Question 11

What colour flame does copper (Cu2+) produce in a flame test?

Answer 11

Blue-green / green-blue