Self Assess 1.5 (Textbook) – Chemistry Form 5 Chapter 1 (Redox Equilibrium)

Question 1:
Name a metal that exists as an element.

Answer:
Silver and aurum.

Question 2:
Explain why aluminium cannot be extracted through reduction reaction by carbon.

Answer:
– Aluminium is more reactive than carbon in the reactivity series of metals.

– Reaction between aluminium oxide and carbon does not occur.

– Carbon cannot reduce aluminium oxide.

Question 3:
Iron is extracted by using a blast furnace:
(a) Write the chemical equation for a redox reaction that produces molten iron.
(b) What is the function of calcium carbonate in the process of iron extraction?

Answer:
(a) $$2 \mathrm{Fe}_2 \mathrm{O}_3+3 \mathrm{C} \rightarrow 4 \mathrm{Fe}+3 \mathrm{CO}_2$$


(b)
– At a high temperature, calcium carbonate, CaCO₃ decomposes to form calcium oxide, CaO (quicklime) and carbon dioxide, CO₂.

– Calcium oxide, CaO reacts with the impurities in iron ore such as silicone(IV) oxide, SiO₂ to form slag or calcium silicate, CaSiO₃.

– This reaction is important to separate the impurities from molten iron.

– The difference in density causes slag to be at the top layer of the molten iron that makes the separation process easier.

Question 4:
Name the metal that can be used to extract copper from copper(II) oxide.
Explain your answer.

Answer:
– Zinc (or Magnesium / Aluminium / Iron / Tin / Lead)

– Zinc is more reactive than copper.

– Zinc can reduce copper(II) oxide to copper.