2.
How is a chemical change different from a physical change?
3.
'Neutralisation reaction is a chemical change. Justify this stateme
help of an example.
4.
Define a decomposition reaction and give an example of the same
5. Classify the following reactions into different types, giving reason
(a) CaO(s) + SiO2(g)
CaSiO,(s)
(b) KOH(aq) + HCl(aq)
→ KCl(aq) + H2O(1)
(c) Cu(s) + 2AgNO,(aq) Cu(NO),(aq) + 2Ag(s)
(d) BaCO(s) BaO(s) + CO,(g)
heat
Answers
Answer: A In a physical change the appearance or form of the matter changes but the kind of matter in the substance does not. However in a chemical change, the kind of matter changes and at least one new substance with new properties is formed. The distinction between physical and chemical change is not clear cut
Answer b Neutralization reaction is a chemical action as it is a double replacement reaction. The example is an acid and base reaction gives salt as its product like Hydrogen Chloride and Sodium Hydroxide gives Sodium Chloride and of course the water as its product.
Answer c A decomposition reaction occurs when one reactant breaks down into two or more products. This can be represented by the general equation: AB → A + B. Examples of decomposition reactions include the breakdown of hydrogen peroxide to water and oxygen, and the breakdown of water to hydrogen and oxygen.
answer 5 (a) is combination reaction as two reactants are combining to give one product.
(b) is a double displacement reaction as potassium, which is more reactive than hydrogen is displacing hydrogen from HCl and H combines with OH to form H2O.
(c) is a displacement reaction as Cu is displacing Ag as Cu is more reactive than Ag.
(d) is a decomposition reaction as one reactant is splitting into two products due to a catalyst.
Hope it helps...