Give an example of each of a chemical reaction evolution of a gas change of colour formation of precipitate
Answers
Answer:
Evolution of a gas:
Simple displacement-
Zn+ H2So4 -> ZnSo4 + H2
Change of Colour:
2Cu(NO3)2 -> 2CuO + 2NO2 + O2
Blue copper nitrate turns black on heating.
Formation of Precipitate:
AgNO3+ NaCl _> NaNO3 + AgCl (insoluble)
Reaction of Silver nitrate with common salt gives Silver chloride precipitate.
Answer:
1. Change in colour :
The reaction between lead nitrate solution and poassium iodide solution.
Chemical equation as follow :
Pb ( NO₃ )₂ + 2 KI ⇒ PbI₂ + 2 KNO₃
In above reaction colour change from colourless to yellow.
2. Change in temperature :
The reaction between dil. sulphuric acid on zinc.
Chemically :
Zn + H₂SO₄ ⇒ ZnSO₄ + H₂
Heat evolved in the above reaction.
3. Formation of precipitation :
The reaction between barium chloride on sodium sulphate.
Chemically :
BaCl₂ + Na₂SO₄ ⇒ BaSO₄ + 2 NaCl
In the above reaction white ppt. of BaSO₄ will form.