Question

Give an example each that illustrates the following characteristics of a chemical reaction:
(a)evolution of a gas
(b)change of colour
(c)change in state ​

Answer 1

Answer:

Explanation:

1. Evolution of gas:

(NH4)2SO4 (aq) + Ca (OH)2 (aq) → CaSO4(s) + 2H2O(l) + 2NH3(g)

When acids react with water hydrogen gas is liberated.  

CaCO3 + 2HCl →→CaCl2 + CO2 + H2O

2. Change in colour :

Rusting of iron ,  colour of iron changes to reddish brown when rusting happens.

CuSO4 + Fe → FeSO4 + Cu

When calcium carbonate reacts with carbon dioxide it forms a yellow substance.

3. Change in state - burning of paper and melting of ice

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Answer 2

Answer:

hydrochloric acid oxidizes zinc to produce an aqueous metal salt and hydrogen gas bubbles. ... The oxidation of metals by strong acids is another common example of a gas evolution reaction.