Heat is produced when
Water is added to concentrated sulphuric acid
Water is added to quick lime
However (a) is a physical change but (b) is a chemical change. Explain the above observation.

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Solution

Physical change are the changes affecting the form of a chemical substance but not its chemical composition, it is a reversible change and no new product is formed.
Chemical change results in the production of new products and it is an irreversible change.
When water is added to sulphuric acid it reacts vigorously, the result is that before and after the property of sulphuric acid is the same,It is an exothermic reaction, No new product is formed so it is a physical change.
b. When water is added to quicklime it forms calcium hydroxide
Heat energy is released
It is an irreversible change so it is a chemical change.

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Two drops of dilute sulphuric acid were added to 1 g of copper sulphate powder and then small amount of hot water was added to dissolve it (step I). On cooling, beautiful blue coloured crystals got separated (step II). Step I and step II are:
(a) physical and chemical changes respectively
(b) chemical and physical changes respectively
(c) both physical change
(d) both chemical change

What would you observe in the following cases?
(i) Sulphur trioxide is dissolved in water on a large scale.
(ii) Concentrated sulphuric acid is added to equal volumes of cold water.
(iii) 100 ml of 98% sulphuric acid is kept open.
(iv) Hot concentrated sulphuric acid is added to sodium chloride crystals.
(v) Dilute sulphuric acid is added to ferrous sulphate solution.

Give reasons for the following :

(a) Sulphuric acid forms two types of salts with NaOH,

(b) Red brown vapours are produced when concentrated sulphuric acid is added to hydrogen bromide,

(d) Brisk effervescence is seen when oil of vitriol is added to sodium carbonate.

Q. which characteristics of a chemical change do u observe when dilute sulphuric acid is added to zinc granules in a conical flask?

Q. Mixing of iron fillings and powdered Sulphur is a physical change but heating this mixture is a
chemical change. Explain it.

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Heat is produced whenWater is added to concentrated sulphuric acid Water is added to quick limeHowever (a) is a physical change but (b) is a chemical change. Explain the above observation.

Heat is produced when
Water is added to concentrated sulphuric acid
Water is added to quick lime
However (a) is a physical change but (b) is a chemical change. Explain the above observation.