Write any two observations in an activity which may suggest that a chemical reaction has taken place. Give an example in support of your answer.
Write any two observations in an activity which may suggest that a chemical reaction has taken place. Give an example in support of your answer.
The following observations in an activity may suggest that a chemical reaction has taken place:
- change in state
- evolution of gas
- change in temperature
- formation of a precipitate
Some of the examples are:
(i) Calcium oxide reacts vigorously with water to produce calcium hydroxide. During this process, a large amount of heat is also evolved, which increases the temperature of the system. This confirms that a chemical reaction has taken place.
CaO(s)+H2O(l)⟶Ca(OH)2(aq)
(ii) When calcium carbonate is heated, it decomposes to form calcium oxide and carbon dioxide. Here, evolution of the gas (carbon dioxide) confirms that a chemical reaction has taken place.
CaCO3⟶CaO+CO2
The following observations in an activity may suggest that a chemical reaction has taken place:
- change in state
- evolution of gas
- change in temperature
- formation of a precipitate
Some of the examples are:
(i) Calcium oxide reacts vigorously with water to produce calcium hydroxide. During this process, a large amount of heat is also evolved, which increases the temperature of the system. This confirms that a chemical reaction has taken place.
CaO(s)+H2O(l)⟶Ca(OH)2(aq)
(ii) When calcium carbonate is heated, it decomposes to form calcium oxide and carbon dioxide. Here, evolution of the gas (carbon dioxide) confirms that a chemical reaction has taken place.
CaCO3⟶CaO+CO2
