Write your observation when the following processes take place:
(a) an aqueous solution of sugar is heated till it gets dried up.
(b) a saturated solution of KCl at 60°C is allowed to cool at room temperature,
(c)a mixture of iron fillings and sulphur powder is heated strongly.
(d) a beam of light is passed through colloidal solution
(e) dil HCl is added to mixture of iron fillings and sulphur powder.
Answers
A....a saturated solution of potassium chloride prepared at 60°C is allowed to cool to room temperature. ... (b) an aqueous sugar solution is heated to dryness. Answer: When an aquoussolution of sugar is heated to dryness, the sugar will be left behind in the container after the vaporization of water
B....When a saturated solution of potassium chloride prepared at 60'C is allowed to cool at room temperature, crystals of potassium chloride will be formed.
C....When iron filings and sulphur powder are mixed, both retain their properties. It means they have not undergone any chemical reaction. Therefore, mixing of iron and sulphur is a physical change. When iron filings and sulphur powder are mixed and heated they undergo a chemical reaction and form ferrous sulphide (FeS).
D....the path of the beam of light is visible through the colloid due to tyndall effect.
E....compound FeS is formed by the reaction between iron filings and sulphur. When dilute HCI is added to part A, FeS will react with dil HCI to form H2S gas which has smell of rotten eggs and will turn lead acetate paper black. ... When dil, HCI is added to it, iron filings react with dill.