write any two observation in an activity which may suggest that a chemical reaction has taken place. give an example in support of your answer
Answers
Answer:
When ferrous sulphate crystals are heated, they lose water of crystallisation and become colourless. On further heating, the ferrous sulphate crystals decompose to form ferric oxide, sulphur dioxide and sulphur trioxide.
2FeSO4 (s) -------> Fe2O3 (s) + SO2 (g) + SO3 (g)
Observations which may suggest that a chemical reaction has taken place are as follows:
1) Gas is evolved
2) Energy in the form of heat is required for the reaction.
3) The physical state of the reactant and the products are different.
4) Colour change is observed.
Answer:
Change in temperature.
Example : Calcium oxide reacts vigorously with water to produce calcium hydroxide along with evolution of large amount of heat. 2) evolution of gas. eg; Zn reacts with H2so4 to form ZnSO4 and H2.
write any two observations in an activity which may suggest that a chemical reaction has taken place. give example in support of your answer.
Answer : A chemical change can be confirmed by the following;
1) change in temperature
eg; calcium oxide reacts vigorously with water to produce calcium hydroxide along with evolution of large amount of heat.
2) evolution of gas
eg; Zn reacts with H2SO⁴ to form ZnSO⁴ and H²
