Perform the following reactions and classify them as physical or chemical changes:
a) Iron with copper sulphate solution in water
b) Burning of magnesium ribbon in air
c) Zinc with dilute sulphuric acid
d) Heating of copper sulphate crystals
e) Sodium sulphate with barium chloride in the form of their solutions in water
Answers
Answer:
A .Reaction of Iron Nails with Copper Sulphate Solution in Water. When an iron nail is dipped in copper sulphate solution, a brown coating of copper is formed on the surface of iron and the colour of copper sulphate solution changes from blue to light green.
B . When the magnesium metal burns it reacts with oxygen found in the air to form Magnesium Oxide. A compound is a material in which atoms of different elements are bonded to one another. Oxygen and magnesium combine in a chemical reaction to form this compound.
C. When dilute sulphuric acid is poured on zinc granules, then zinc being more reactive than hydrogen displaces it from the acid and forms zinc sulphate and hydrogen gas.
D. Copper sulphate crystals contain water of crystallisation (CuSO4. 5H2O). On heating, hydrated copper sulphate loses its water molecule and forms white coloured anhydrous copper sulphate.
E. On adding sodium sulphate to barium chloride, white precipitate is immediately formed which is insoluble in dil. HCl. 1. Sodium sulphate chemically reacts with barium chloride in the form of their aqueous solution to form a white precipitate of barium sulphate.
1.chemical
2.chemical
3.chemical
4.physical
5.chemical
Explanation:
The brown coating on the iron nail indicates that copper is deposited on the iron nail as a result of iron displacement.
2. The colour of the blue colour copper sulphate solution changes to green.
3. The greenish colour of the solution in the test tube indicates the presence of Fe2+ ions in the solution.
4. This is a single displacement reaction in which copper is displaced by iron from copper sulphate solution, resulting in the formation of a new compound, ferrous sulphate.
5. A chemical change occurs as a result of the reaction.