Question

write chemical equation.a) a piecpie of calcium is added to water.b)stream is passed over red hot iron

Answer 1

(a) When a Piece of the Calcium is added to the Water, Calcium Hydroxide (or Slacked lime), which is the basic hydroxide is produced and along with the Hydrogen gas is evolved.

Reaction is ⇒
Ca + 2H₂O ---------→ Ca(OH)₂ + H₂↑

(b) When the Steam is passed over red hot iron, Iron(III) Oxide and Hydrogen gas is formed.
 
Reaction is ⇒
   3Fe + 4H₂O -----------→ Fe₃O₄ + 4H₂↑

Note ⇒ Iron does not reacts with the water under ordinary temperature. It only reacts with the steam.



Hope it helps.

Answer 2

When Calcium is added to water, the following reaction takes place

Ca + 2H₂O → Ca(OH)₂ + H₂↑

When steam is passed over red hot iron, the following reaction takes place

3Fe + 4H₂O(g) → Fe₃O₄ + 4H₂↑

Fe₃O₄ is a mixed ore of iron (FeO.Fe₂O₃) called magnetite.