CI 3 - Inorganic Chemistry and the Periodic Table

Question 1

What is the bonding like in nitrogen gas?

Answer 1

Nitrogen has a strong triple bond, making it very unreactive

Question 2

What is the bonding like in ammonia, NH3?

Answer 2

There are 3 bonding electron pairs (covalent bonds between nitrogen and hydrogen) and 1 lone pair so the bond shape is pyramidal, 107 degrees

Question 3

What is the bonding like in ammonium ions?

Answer 3

There are 4 bonding pairs and no lone pairs
One of the covalent bonds is dative
The bond shape is tetrahedral and the bond angle is 109.5 degrees

Question 4

What are the names of N2O, NO and NO2?

Answer 4

N2O = Nitrous oxide
NO = Nitric oxide
NO2 = Nitrogen dioxide

Question 5

How do N2O, NO and NO2 appear?

Answer 5

N2O = Colourless gas
NO = Colourless gas
NO2 = Reddish-brown gas

Question 6

What is the interconversion of the nitrate (V) ion, nitrate (III) ion and the ammonium ion?

Answer 6

Step 1: 2NH4+ + 3O2 –> 2NO2- + 2H2O + 4H+
Step 2: 2NO2- + O2 –> 2NO3-

Question 7

How are nitrate ions converted to ammonium ions?

Answer 7

NO2- + 6e- + 8H+ –> NH4+ + 2H2O

Question 8

How are nitrite ions reduced to nitric oxide?

Answer 8

NO2- + e- + 2H+ –> NO + H2O

Question 9

How is nitric oxide reduced to nitrous oxide?

Answer 9

2NO + 2e- + 2H+ –> N2O + H2O

Question 10

How do you test for nitrate (V) ions?

Answer 10

1. Warm the sample with NaOH and Devarda’s alloy (an alloy of aluminium, copper and zinc)
2. Test the gas produced with damp red litmus paper
3. If it turns blue this confirms the presence of nitrate (V) ions

Question 11

How do you test for ammonium, NH4+ ions?

Answer 11

1. Warm the sample with sodium hydroxide
2. Test the gas released with a damp piece of red litmus paper
3. If it goes blue, this confirms the presence of the ammonium ion