Chemistry
Differentiate between Direct combination reaction & a decomposition reaction.
Answer
Difference between direct combination reaction & a decomposition reaction:
| Direct combination reaction | Decomposition reaction |
|---|---|
| It is a reaction in which two or more elements or compounds combine to give a new product. | It is a reaction in which a chemical compound decomposes into two or more simpler substances. |
| Example: Fe + S ⟶ FeS | Example: CuCO3 ⟶ CuO + CO2 |
Related Questions
State what is a chemical reaction. A chemical reaction is often accompanied by external indications or characteristics which include
(a) Colour change
(b) Effervescence or gas evolved
(c) Evolution or absorption of heat
(d) Formation of a precipitate
With reference to each of the above indications, state the external indication seen during
(i) Addition of dilute acid to an active metal
(ii) Addition of dilute hydrochloric acid to silver nitrate
(iii) Addition of water to quicklime
(iv) Thermal decomposition of mercury [II] oxide
State why a direct combination reaction is called a - 'synthesis reaction'.
Differentiate between Displacement reaction & a neutralization reaction.
Classify the following reactions into
(a) Direct combination
(b) Decomposition
(c) Displacement
(d) Double decomposition
The reactions are
(i) Zinc hydroxide on heating gives zinc oxide & water
(ii) Zinc reacts with copper [II] sulphate to give zinc sulphate & copper
(iii) Zinc sulphate reacts with ammonium hydroxide to give ammonium sulphate & zinc hydroxide
(iv) Molten zinc at high temperatures, burns in air to give zinc oxide.