Write any two observations in an activity which may suggest that a chemical reaction has taken place. Give the examples in support of your answer.


Share with your friends
Call

i. In an activity, when any of the following occurs, it suggests that a chemical reaction has taken place:
a. change in state
b. change in colour
c. change in temperature
d. evolution of gas
ii. In an activity, change in state and evolution of gas indicate that a chemical reaction has taken place:
eg. Magnesium reacts with hydrochloric acid to give aqueous magnesium chloride and hydrogen gas.
iii. In an activity, change in state and change in temperature indicate that a chemical reaction has taken place:

eg. Calcium oxide reacts vigorously with water to produce slaked lime (calcium hydroxide) releasing a large amount of heat.

CaO(s) + H2O(l) → Ca(OH)2(aq) + Heat