4.3.3 - Laboratory Activity : Studying the reaction of alkali metals with halogens

Laboratory Activity 4.3.3: Studying the reaction of alkali metals with halogens

Aim: To study the reaction of alkali metals with halogens
Problem statement: How do lithium, sodium and potassium differ in reactivity with chlorine gas?
Hypothesis: Reactivity increases for the reaction between alkali metals and chlorine gas when going down Group 1
Variable:

	»	Fixed variable : Concentration of chlorine gas
	»	Manipulated variable : Type of alkali metal
	»	Responding variable : Reactivity of the metal with chlorine gas

Material: » Lithium » Sodium » Potassium » Filter paper

Apparatus: » Gas jar with cover » Gas jar spoon » Small knife » Test tube » Forceps » Bunsen burner

Procedure:

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1. The animation below shows the procedures and observation of the experiment. 2. A small piece of lithium is cut with a knife. Dry it with filter paper 3. The lithium is placed in the gas jar spoon by using a forceps. 4. The lithium is heated until it begins to burn, then it is plunged into a gas jar filled with chlorine. All observation are recorded. 5. The experiment is repeated using sodium and potassium.

Results:

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Metal Observation Lithium Burns slowly with a red flame. Forms a white solid. Sodium Burns quickly with a bright yellow flame. Forms a white solid. Potassium Burns vigorously with a brilliant purple flame. Forms a white solid.

Discussion:

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Lithium, sodium and potassium react with chlorine to produce a white metallic chloride. ○ $\mathrm{2Li(s)\; +}{\mathrm{Cl}}_2\mathrm{(g)}\to \mathrm{2LiCl(s)}$ ○ $\mathrm{2Na(s)\; +}{\mathrm{Cl}}_2\mathrm{(g)}\to \mathrm{2NaCl(s)}$ ○ $\mathrm{2K(s)\; +}{\mathrm{Cl}}_2\mathrm{(g)}\to \mathrm{2KCl(s)}$

Conclusion:

	►	All Group 1 metals react with chlorine to form a metallic chloride.
	►	The reactivity increases down the Group 1.
	►	The hypothesis is accepted.

↶ 4.3 Group 1 Elements

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