Eletronegatividade

Tungsten can be extracted from its oxide, WO₃, by heating it with carbon monoxide. Carbon dioxide is produced as shown below.

WO₃+ 3CO → W + 3CO₂

Explain, in terms of oxidation state, why tungsten in tungsten oxide has been reduced.

In a reaction, MnO₄^- is converted to Mn²⁺. Explain, in terms of electron transfer, if manganese (Mn) is oxidised or reduced.

WRITE THIS OUT ON PAPER, YOU MAY USE THE ANSWER TO THIS PROBLEM AGAIN IN ANOTHER QUESTION:

Consider the following REDOX reaction:

Cl₂(g) → ClO⁻(aq) + Cl⁻(aq) (basic solution)

Which species is the result of oxidation?

• Cl⁻

• ClO⁻

Substance X changes aqueous potassium iodide from colourless to brown and changes aqueous potassium manganate(VII) from purple to colourless. Which statement correctly describes X?

• It is an oxidising agent only.

• It is a reducing agent only.

• It is an oxidising agent and a reducing agent.

• It is neither an oxidising agent nor a reducing agent.

What element is being Reduced?

• N
• H
• O
• S

What element is being Oxidized?

• I⁰

• H⁺¹

• S⁺⁴

• O^-2

What element is being reduced?

• I⁰

• H⁺¹

• S⁺⁴

• O^-2

Ammonia reacts with chlorine as shown:

2NH₃ + 3Cl₂ → N₂ + 6HCl

State the oxidising agent.

Explain your answer.

What element is being Reduced?

• N⁺⁵

• H⁺¹

• O^-2

• S^-2

A drop of solution S turns acidified potassium dichromate(VI) to green chromium(III) ion.

What does solution S behave as?

• an acid

• an oxidising agent

• a reducing agent

• neither oxidising nor reducing agent