Page 89 - Chemistry ICSE Class IX

Water 77

Metal Reaction conditions Reaction
Iron (Fe) Red-hot iron reacts with steam to liberate 3Fe(s) + 4H O o Fe O (s) + 4H (g)
4
2
2
3
hydrogen. red hot steam iron(II, III) oxide
(ferrosoferric oxide)
Copper (Cu) No reaction even with steam and at red Cu + H O o No reaction
2
heat. copper
From the results obtained above, we see that sodium reacts with cold
water, magnesium reacts with boiling water, aluminium reacts slowly with
boiling water, zinc decomposes boiling water slowly but steam rapidly, iron
reacts with steam only at red heat, copper does not react even with steam on
heating strongly. Thus, we conclude that
ƒ Magnesium is less reactive than sodium.
ƒ Aluminium is less reactive than magnesium.
ƒ Zinc is less reactive than aluminium.
ƒ Iron is less reactive than zinc.
ƒ Copper is less reactive than iron.
Thus, the order of reactivity of these metals (Activity series) with
water is
Na > Mg > Al > Zn > Fe > Cu
most reactive least reactive
reactivity decreases

Importance and Uses of Water

What is the importance of water for humans and animals
Water is considered to be the source of life. It is important for animal life tĞ ŶĞĞĚ ǁĂƚĞƌ ĨŽƌ ĚƌŝŶŬŝŶŐ͕
because of the following reasons: ĐŽŽŬŝŶŐ͕ ĐůĞĂŶŝŶŐ͕ ĂŶĚ ŝŶ ĂŐƌŝĐƵůƚƵƌĞ͕
ƚƌĂŶƐƉŽƌƚĂƟŽŶ͕ ŚLJĚĞů ƉŽǁĞƌ
ƒ Water is a vital body uid which is essential for regulating various ƐƚĂƟŽŶƐ͕ ĞƚĐ͘
processes, such as digestion, transport of nutrients and excretion. Water
dissolves ionic and a large number of polar organic compounds. Thus,
it transports the products of digestion to the place of requirement in
the body.
ƒ Water regulates the body temperature by the process of sweating and
evaporation.
ƒ Water is a medium for all metabolic reactions in the body. All metabolic
reactions in the body take place in solution phase.
ƒ Water provides habitat to various animals in the form of rivers, sea, etc.

What is the importance of water for plants

Water is important for plants because of the following reasons:
ƒ It helps in the germination of seeds.
ƒ It helps in the process of photosynthesis by which plants prepare their
food.
ƒ It helps in the transport of nutrients and minerals from the soil to the
plants.
ƒ It helps in the maintenance of plant structure by providing the
appropriate pressure to the plant tissues.
ƒ It provides habitat in the form of ponds, rivers, lakes and sea to a large
number of plants.