The metal whose oxide can be reduced by common reducing agents:
(a) Copper
(b) Sodium
(c) Aluminium
(d) Potassium
Ans: (a) Copper
Understanding Metal Oxide Reduction
Metal oxides are compounds formed when metals react with oxygen. To extract the pure metal, the oxygen must be removed, a process known as reduction. This is achieved using a reducing agent, a substance that donates electrons and facilitates the removal of oxygen.
- Reactivity Series: The reactivity series of metals is crucial in determining which metals can be reduced by common reducing agents. Metals higher in the series are more reactive and have a greater affinity for oxygen, making their oxides harder to reduce.
- Common Reducing Agents: Common reducing agents include carbon (in the form of coke), carbon monoxide, and hydrogen.
Why Copper?
- Copper is relatively low in the reactivity series. This means its oxide (copper oxide, CuO) is less stable and can be readily reduced by common reducing agents like carbon.
- The reaction with carbon is a classic example:
- 2CuO(s)+C(s)→2Cu(s)+CO2(g)
Why the Other Options Are Incorrect
- Sodium (b), Aluminium (c), and Potassium (d):
- These metals are highly reactive and occupy high positions in the reactivity series.
- Their oxides (Na₂O, Al₂O₃, and K₂O) are extremely stable and require powerful reducing agents, such as electrolysis, to be reduced.
- Aluminium oxide for example is an amphoteric oxide, and is very stable.
- Potassium and sodium oxides are very reactive with water, and are extremely stable.
Key Concepts
- Reactivity Series: A list of metals arranged in order of their reactivity, with the most reactive at the top.
- Reduction: The gain of electrons or the removal of oxygen.
- Oxidation: The loss of electrons or the addition of oxygen.
- Electrolysis: A process that uses an electric current to drive non-spontaneous chemical reactions.
Practical Applications
- The reduction of copper oxide with carbon is a fundamental process in copper extraction.
- The extraction of highly reactive metals like sodium and aluminium requires specialized techniques, such as electrolysis, due to the stability of their oxides.
Understanding metal oxide reduction is essential in metallurgy and provides insights into the reactivity of metals and the principles of chemical reactions.
