Question

Write the observations for the following chemical reaction.

a) Magnesium ribbon is burnt in air.

b) Ammonia solution and HCl solution is passed through a long glass tube plugged from both

ends.

c) Copper nitrate crystals are strongly heated.

d) Zinc granules are added to copper sulphate solution.

e) Silver nitrate added to sodium chloride solution.

f) Aqueous copper sulphate solution is added to sodium hydrogen solution.
. ​

Answer 1

a) The ribbon burns with a bright white light. Intense heat is also produced in this reaction. Here, when magnesium burns, it reacts with the oxygen found in air to form a powdery ash called magnesium oxide.

b) A white ring of solid ammonium chloride forms where the two gases meet inside the tube. NH3 + HCl →  NH4Cl

c) When copper nitrate is heated in the test tube, it decomposes into copper oxide, nitrogen dioxide and oxygen gas. Initially, a molecule of water is lost and on further heating, we get nitrogen dioxide and oxygen gas. So, we observe reddish-brown fumes of nitrogen dioxide that are emitted.

d) When zinc is added to copper sulfate (CUSO4) solution due to more reactivity of zinc, cooper is replaced by the zinc and forms zinc sulfate. During the process, the color of the solution changes from blue to colorless.

e) When silver nitrate solution is added to sodium chloride solution, then a white precipitate of silver chloride is formed along with a sodium nitrate solution.

f) Copper sulphate solution reacts with sodium hydroxide solution to form a precipitate of copper hydroxide according to the equation : 2NaOH+CuSO4​→Na2​SO4​+Cu(OH)2

Answer 2

a) When Magnesium ribbon is burnt in the air in the presence of it a bright white light produced intense heat. magnesium oxide is formed.

b) We know that when Ammonia solution and HCl solution is passed through a long glass tube plugged from both  ends the ammonium chloride is formed.

 NH3 + HCl →  NH4Cl

c) When copper nitrate crystals are strongly heated in the test tube, it decomposes into copper oxide, nitrogen dioxide and oxygen gas.  the nitrogen dioxide and oxygen gas are produced.

d) When zinc granules are added to copper sulfate solution, zinc sulfate is formed.

e) When silver nitrate solution is added to sodium chloride solution,  silver chloride, and sodium nitrate solution is produced.

f)  When Copper sulfate solution is added to sodium hydrogen solution,

 a precipitate of copper hydroxide is formed.

2NaOH+CuSO4​→Na2​SO4​+Cu(OH)2