Problem 51 - Chemistry: The Central Science

Question

Write the chemical formula for each of the following compounds, and indicate the oxidation state of nitrogen in each: (a) sodium nitrite, (b) ammonia, (c) nitrous oxide, (d) sodium cyanide, (e) nitric acid, (f) nitrogen dioxide, (g) nitrogen, (h) boron nitride.

Step-by-Step Solution

Answer

(a) Sodium nitrite: Chemical formula is NaNO2 and the oxidation state of nitrogen is +3. (b) Ammonia: Chemical formula is NH3 and the oxidation state of nitrogen is -3. (c) Nitrous oxide: Chemical formula is N2O and the oxidation state of nitrogen is +1.5 (average). (d) Sodium cyanide: Chemical formula is NaCN and the oxidation state of nitrogen is -3. (e) Nitric acid: Chemical formula is HNO3 and the oxidation state of nitrogen is +5. (f) Nitrogen dioxide: Chemical formula is NO2 and the oxidation state of nitrogen is +4. (g) Nitrogen: Chemical formula is N2 and the oxidation state of nitrogen is 0. (h) Boron nitride: Chemical formula is BN and the oxidation state of nitrogen is -3.

Step 1: (a) Sodium nitrite

1. Chemical formula: Sodium (Na) is an alkali metal that has a +1 charge when it loses an electron, and Nitrite (NO2-) is a polyatomic ion with a total charge of -1. Combining these two ions in the ratio 1:1, we get the chemical formula NaNO2. 2. Oxidation state of nitrogen: Nitrogen is bonded to two oxygens and has one unshared electron. Thus, its oxidation state is +3.

Step 2: (b) Ammonia

1. Chemical formula: Ammonia comprises one nitrogen atom and three hydrogen atoms bonded together; thus, its formula is NH3. 2. Oxidation state of nitrogen: Nitrogen has one lone pair and three single bonds to hydrogen atoms. Thus, its oxidation state is -3.

Step 3: (c) Nitrous oxide

1. Chemical formula: Nitrous oxide is a compound composed of two nitrogen atoms and one oxygen atom, arranged linearly. Thus, its chemical formula is N2O. 2. Oxidation state of nitrogen: Due to the resonance structure of the molecule, one nitrogen atom has an oxidation state of +1, and the other nitrogen atom has an oxidation state of +2 (average oxidation state of +1.5).

Step 4: (d) Sodium cyanide

1. Chemical formula: Sodium (Na) has a +1 charge, and the cyanide ion (CN-) has a -1 charge. Combining these ions in the ratio 1:1, we get the chemical formula NaCN. 2. Oxidation state of nitrogen: Nitrogen is triple bonded to carbon and has one lone pair. Thus, its oxidation state is -3.

Step 5: (e) Nitric acid

1. Chemical formula: Nitric acid consists of one nitrogen atom, one hydrogen atom, and three oxygen atoms. Thus, its chemical formula is HNO3. 2. Oxidation state of nitrogen: Nitrogen is bonded to three oxygen atoms (two in double bonds and one in a single bond) and one hydrogen atom. Thus, its oxidation state is +5.

Step 6: (f) Nitrogen dioxide

1. Chemical formula: Nitrogen dioxide has one nitrogen atom and two oxygen atoms. Thus, its chemical formula is NO2. 2. Oxidation state of nitrogen: Nitrogen is bonded to two oxygen atoms and has an unshared electron. Thus, its oxidation state is +4.

Step 7: (g) Nitrogen

1. Chemical formula: Nitrogen occurs as a diatomic molecule in the atmosphere, with two nitrogen atoms bonded together. Thus, its chemical formula is N2. 2. Oxidation state of nitrogen: Nitrogen is bonded to another nitrogen atom, with each nitrogen having three unshared electrons. Thus, its oxidation state is 0.

Step 8: (h) Boron nitride

1. Chemical formula: Boron nitride (BN) is a compound composed of alternating boron and nitrogen atoms bonded together in a hexagonal lattice structure. The chemical formula is BN. 2. Oxidation state of nitrogen: Nitrogen has three single bonds to three boron atoms and one lone pair. Thus, its oxidation state is -3.