write any 2 observations in an activity which may suggest that a chemical reaction has taken plas with examples
write any 2 observations in an activity which may suggest that a chemical reaction has taken plas with examples
Some examples are
1. evolution of a gas
In reactions of metals with acids, H2 gas is evolved which can be detected by a pop sound upon burning.
b. In the decomposition of calcium carbonate by heating, CO2 is evolved which can be detected by lime water turning milky white.
2. formation of a precipitate
a. In the reaction of Barium chloride and potassium sulphate, a precipitate of barium sulphate is formed.
3. Change of colour
a. in some titration reactions, we often see a change of colour of indicator as a signal of completion of the reaction.
b. In the reaction of Copper sulphate with zinc, the blue colour of the solution disappears due to the formation of zinc sulphate.
4. Change in temperature
a. some reactions involving acid-base neutralisation causes the evolution of heat which can be detected by a change in temperature.
Some examples are
1. evolution of a gas
In reactions of metals with acids, H2 gas is evolved which can be detected by a pop sound upon burning.
b. In the decomposition of calcium carbonate by heating, CO2 is evolved which can be detected by lime water turning milky white.
2. formation of a precipitate
a. In the reaction of Barium chloride and potassium sulphate, a precipitate of barium sulphate is formed.
3. Change of colour
a. in some titration reactions, we often see a change of colour of indicator as a signal of completion of the reaction.
b. In the reaction of Copper sulphate with zinc, the blue colour of the solution disappears due to the formation of zinc sulphate.
4. Change in temperature
a. some reactions involving acid-base neutralisation causes the evolution of heat which can be detected by a change in temperature.
