Electrochemistry

What oxidation states can nitrogen assume?

Nitrogen can assume oxidation states from -3 to +5.

What is the Haber process used for?

The Haber process is used to synthesize ammonia (NH₃) from hydrogen (H₂) and nitrogen (N₂) at low temperature with a catalyst.

Name some common products that contain phosphorus.

Phosphorus is found in soaps, toothpaste, fertilizers, pesticides, and nucleic acids (DNA).

Why is phosphate use being discouraged?

Phosphates contribute to algae blooms, which harm aquatic ecosystems.

What is the most manufactured chemical, and what is its production process?

Sulfuric acid (H₂SO₄) is the most manufactured chemical. It is made by the Claus and contact process, converting H₂S from petroleum into H₂SO₄.

What are halides, and what are their properties?

Halides have small radii, high ionization energy, high electronegativity, and form -1 anions. Their oxides and hydrides are acidic.

How does fluoride (F⁻) protect teeth?

Fluoride replaces hydroxide (OH⁻) in tooth enamel, making it more resistant to decay.

What is chlorine (Cl₂) used for?

Chlorine is a strong oxidizing agent used in disinfection, sanitation, and PVC production.

What are some specialty uses of noble gases?

Noble gases are used as cryogens (He), inert gases (Ar), and in lighting (Ne).

Which species in bleach makes it an effective disinfectant?

Chlorine (Cl₂) – It is a strong oxidizing agent used in disinfection and sanitation.

What are the reactants and products of the wet method?

Reactants: Ca₁₀(PO₄)₆F₂, H₂SO₄
Products: H₃PO₄ (Phosphoric acid)

What does the Claus process do?

The Claus process converts hydrogen sulfide (H₂S) into elemental sulfur (S) through a two-step oxidation process.

What is the reactant and product of the Contact process?

Reactant: Sulfur (S)
Product: Sulfuric acid (H₂SO₄)

How do the Claus and Contact processes work together?

The Claus process produces elemental sulfur (S) from H₂S, and the Contact process oxidizes S to produce sulfuric acid (H₂SO₄).

Why is sulfuric acid the most manufactured chemical in the world?

It is widely used in industrial processes, especially in fertilizer production, where it solubilizes phosphate from rocks.

How does sulfuric acid aid in phosphate extraction?

Sulfuric acid solubilizes phosphate from rocks in the wet method, which is essential for fertilizer production.

Besides being a strong acid, what other properties does sulfuric acid have?

Sulfuric acid is also a strong oxidizing agent and a strong dehydrating agent (removes water).

What contaminant in natural gas is removed by the Claus process?

Hydrogen sulfide (H₂S) is removed and converted into elemental sulfur.

What is the key concept behind redox reactions in electrochemistry?

Redox reactions are based on the changing oxidation numbers of compounds during a reaction.

In the reaction 2 MnO₄⁻ + 16 H⁺ + 10 I⁻ → 2 Mn²⁺ + 8 H₂O + 5 I₂, what has been reduced, and what is its oxidation number change?

Manganese (Mn) is reduced from +7 to +2.

What happens to iodine in the reaction 2 MnO₄⁻ + 16 H⁺ + 10 I⁻ → 2 Mn²⁺ + 8 H₂O + 5 I₂?

Iodine (I⁻) is oxidized from -1 to 0.

What is the oxidation number of oxygen in most compounds?

-2, unless exceptions apply (e.g., peroxides, superoxides).

What are the oxidation number rules for free elements and individual ions?

Free elements = 0 (e.g., Cl₂, Mg). Individual ions = their charge (e.g., Al³⁺ = +3, Mn²⁺ = +2).

What is the oxidation number of hydrogen in most compounds?

+1, unless bonded to metals in hydrides (e.g., NaH, where H = -1).

What is the oxidation number assignment for different groups on the periodic table?

• Group I: +1

• Group II: +2

• Group III: +3 or -5

• Group IV: +4 or -4

• Group V: -3 or +5

• Group VI: -2

• Group VII: -1

What does OIL RIG stand for in redox chemistry?

Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons).