Chemistry key definitions and test 2

Question 1

Write the symbols for these compounds ions…
Carbonate
Sulfate
Ammonium

Answer 1

CO3 2-
SO4 2-
NH4 +

Question 2

How do we test for carbonate ion and what is the positive result?

Answer 2

Add acid - fizzes
Bubble gas through limewater - goes cloudy.

Question 3

How do you carry out a flame test? 4 steps.

Answer 3

Using nichrome wire, put sample into a blue (non-luminous) flame. Note colour of flame.

Question 4

Two solutions used when testing for the sulfate ion, and what is the positive result of this test?

Answer 4

Hydrochloric acid, Barium chloride.
White precipitate.

Question 5

Two Solutions used when testing for a halide ion?

Answer 5

Nitric acid
Silver nitrate.

Question 6

What are the colours of the precipitates formed with…
Chloride ions
bromide ions
iodide ions

Answer 6

White
Cream
Yellow

Question 7

How do we test for the ammonium ion and what is the positive result?

Answer 7

Add sodium hydroxide solution and warm.
Gas formed changes damp red litmus from red to blue.

Question 8

Precipitation reactions using sodium hydroxide can be used to identify some transition metals. Give the symbols for the metal ions that produces, each of the following…
A blue precipitate
a green precipitate
an orange precipitate

Answer 8

Copper (II)
Iron (II)
Iron (III)

Question 9

Three reasons why nichrome (or platinum) wire is suitable for flame testing.

Answer 9

Doesn’t colour flame.
Doesn’t burn/react.
High melting point.

Question 10

Why is a blue flame use rather than a luminous yellow flame?

Answer 10

Masks metal flame colour.

Question 11

Flame colours for the the following:
Lithium
Sodium
Potassium
Calcium
Barium

Answer 11

Red
Yellow
Lilac
Orange-red
Blue-green