Chemistry
Write balanced equations and give your observations when the following metals react:
(i) Sodium with cold water
(ii) Calcium with cold water
(iii) Magnesium with boiling water
(iv) Magnesium with steam.
Answer
(i) When Sodium reacts with cold water, it melts, forming a silvery globule, which darts about on the surface of water. It catches fire and burns with a golden yellow flame. Bubbles of hydrogen gas are liberated. The solution formed is colourless, soapy, slightly warm and alkaline.
2Na + 2H2O ⟶2NaOH + H2 ↑
(ii) Calcium sinks in water and the reaction is less vigorous than Sodium. Bubbles of hydrogen gas are liberated and the solution turns milky, turbid and alkaline. If red litmus is introduced in solution, it turns blue.
Ca + 2H2O ⟶ Ca(OH)2 + H2 ↑
(iii) Magnesium reacts slowly with boiling water and forms a base, magnesium hydroxide, liberating hydrogen gas.
Mg + 2H2O ⟶ Mg(OH)2 + H2 ↑
(iv) Magnesium burns in steam with an intense white light, liberating hydrogen gas and white ash which is magnesium oxide.
Mg + H2O ⟶ MgO + H2 ↑
Magnesium oxide crumbles down due to heating. Further exposing magnesium to steam results in the liberation of hydrogen gas.
Related Questions
Why are zinc and aluminium considered to have a unique nature. Give balanced equations to support your answer.
Write balanced equations for the following
(i) Iron reacts with dil. HCl
(ii) Zinc reacts with caustic soda solution
(iii) Lead reacts with potassium hydroxide,
(iv) Aluminium reacts with fused sodium hydroxide
(i) Under what conditions iron reacts with water?
(ii) Give the balanced equation of the reaction.
(iii) What is noticed if the products are not allowed to escape?
From the knowledge of activity series, name a metal which shows the following properties:
(i) It reacts readily with cold water
(ii) It displaces hydrogen from hot water
(iii) It displaces hydrogen from dilute HCl
(iv) It forms a base which is insoluble in water.