NCERT Solution for Class Tenth Science Chapter 3
Metals and Non-metals
CBSE NCERT Book Session-2022-2023
Intext Questions
Page No-46
Questions No-2
Write equations for the reactions of (i) iron with steam (ii) calcium and potassium with water.
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(i) Reaction of iron with steam:
3Fe(s) + 4H₂O(g) → Fe₃O₄(s) + 4H₂(g)
This reaction involves the formation of iron(II,III) oxide (Fe₃O₄), also known as magnetite, and hydrogen gas.
(ii) Reaction of calcium with water:
Ca(s)+2H₂O(l) → Ca (OH)₂ (aq) + H₂(g)
Calcium reacts with water to form calcium hydroxide (Ca (OH)₂) and hydrogen gas.
(iii) Reaction of potassium with water:)
2K(s) +2H₂O(l) → 2KOH(aq) + H₂(g)
Potassium reacts with water to produce potassium hydroxide (KOH) and hydrogen gas. The reaction of alkali metals like potassium with water is generally more vigorous compared to alkaline earth metals like calcium.
(i) Iron reacts to steam to form ferrous oxide and hydrogen gas.
3Fe(s) + 4H₂O(g) → Fe3O4(s) + 4H₂(g)
(ii) Calcium reacts with water and forms calcium hydroxide commonly known as slaked lime.
Ca(s) + 2H₂O(l) → Ca(OH) ₂ (aq) + H₂ (g)
2K(s) + 2H₂O(l) → 2KOH(aq) + H₂(g) + heat energy
(i) Iron react with steam to form the metal oxide and hydrogen.
3Fe(s) + 4H₂O(g) → Fe3O4(s) + 4H₂(g)
(ii) The reaction of calcium with water is exothermic but the heat evolved is not sufficient for the hydrogen to catch fire.
Ca(s) + 2H₂O(l) → Ca(OH) ₂ (aq) + H₂ (g)
Calcium starts floating because the bubbles of hydrogen gas formed stick to the surface of the metal.
Potassium react violently with cold water and its reaction is so violent and exothermic that the evolved hydrogen immediately catches fire.
2K(s) + 2H₂O(l) → 2KOH(aq) + H₂(g) + heat energy
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