Some chemical equations are given in the box. Classify them and tabulate,
Zn+CuSO, ZnSO, +Cu
KCI + AgNO, --AgCl + KNO,
2KCIO, 2KCI +30,
N. +3H 2NH
21,0 21,0 +0
CaO+H,OẠCa(OH),
CH, +Cl, CH CI+ HCI
NaOH + NH,Cl → NaCl + NH OH
Displacement
reaction
Combination
reaction
Decomposition
reaction
Double
decomposition
Answers
Answer:
1. Why should a magnesium ribbon be cleaned before it is burnt in air?
Ans: Magnesium is an very reactive metal. When stored, it reacts with oxygen to form a layer of magnesium oxide on its surface. This layer of magnesium oxide is quite stable and prevents further reaction of magnesium with oxygen. The magnesium ribbon is cleaned by sand paper for removing this layer so that the underlying metal can be exposed to air.
2. Write the balanced equation for the following chemical reactions.
(a) Hydrogen + Chlorine → Hydrogen chloride
(b) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride
(c) Sodium + Water → Sodium hydroxide + Hydrogen
Ans: (a) H2 (g) + Cl2 (g) → 2HCl (g)
(b) 3BaCl2 (s) + Al2(SO4)3 (s) → 3BaSO4(s) + 2AlCl3 (s)
(c) (c) 2Na(s) + 2H2O (l) → 2NaOH (aq) + H2 (g)
3. Write a balanced chemical equation with state symbols for the following reactions.
(a) Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.
(b) Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.
Ans: (a) BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (s) + 2NaCl (aq)
(b) NaOH (aq) + HCl (aq) → NaCL (aq) + H2O (l)
Answer:
first reaction is displacement reaction
second reaction is double displacement reaction
third reaction is combination reaction
fourth reaction is combination reaction
fifth reaction is substitution reaction
sixth reaction is double displacement reaction