3.3.1 - Laboratory Activity : Reactivity of metals with oxygen

Laboratory Activity 3.3.1: Reactivity of metals with oxygen

Aim: To compare the reactivity of metals towards oxygen.
Problem statement: How to build a reactivity series by reacting metals with oxygen?
Hypothesis: Different metal react at different levels with oxygen.
Variable:

	»	Fixed variable : Quantity of metals
	»	Manipulated variable : Type of metals
	»	Responding variable : Reactivity towards oxygen

Material: » Magnesium powder » Zinc powder » Lead powder » Aluminium powder » Copper powder » Potassium manganate (VII)

Apparatus: » Test tubes » Glass wool » Bunsen burner

Procedure:

	►	The animation below shows the arrangement of the apparatus and the observation of the experiment.
	►	1. Magnesium powder, glass wool and potassium manganate (VII) are placed in a test tube as shown above 2. Heat the magnesium powder until it glows, followed by the heating of potassium manganate (VII). 3. The reactivity of the burning of magnesium, the colour of product (cold and hot are recorded. 4. The experiment is repeated by using different metals powder.

Observation:

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Metals Observation Mg Very reactive with very bright glow Zn Bright glow. The powder formed is yellow when hot and white when cold. Fe Yellowish glow and black oxide formed Pb Red hot and glow slowly. The powder formed is orange when hot and yellow when cold. Cu Almost do not glow at all. Black powder formed.

Analysis:

	►	Based on the observation, the reactivity series can be constructed. Metals Conclusion Chemical equation Mg Very reactive 2Mg(s) + O2(g) → 2MgO(s) Zn Reactive 2Zn(s) + O2(g) → 2ZnO(s) Fe Moderately reactive 4Feg(s) + 3O2(g) → Fe2O3(s) Pb Least reactive 2Pb(s) + O2(g) → 2PbO(s) Cu Almost non-reactive 2Cu(s) + O2(g) → 2CuO(s)
	►	The more reactive metals will burn faster with a brighter flame than less reactive metals. Therefore, the reactivity series that are arranged based on the reactions with oxygen is Mg, Zn, Fe, Pb, Cu (in decreasing order with Mg being the most reactive and Cu almost non-reactive)

Discussion:

	►	Oxygen is produced when potassium permanganate (VII) is heated. ○ 2KMnO4(s) → K2MnO4(s) + MnO2(s) + O2(g)
	►	The glass wool is to separate the potassium manganate (VII) and the metal powder. An explosion is likely to occur if very reactive metal powder is heated together with potassium manganate (VII).

Conclusion:

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Different metal react at different levels with oxygen. Hypothesis is accepted.

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