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A CHEMICAL REACTION IS CHARACTERIZED BY EVOLUTION OF A GAS AND BY EVOLVING HEAT (EXOTHERMIC REACTION).

Take a few zinc granules in a conical flask. Add dilute hydrochloric acid (HCl) or sulphuric acid (H2SO4) in the conical flask. (a) What do you observe ? (b) Touch the conical flask and observe any change in its temperature ? Objective – A chemical reaction characterized by evolution of a gas and by evolving heat …

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COMBINATION REACTION

Slowly add water in a small amount of calcium oxide or quick lime containing in a conical flask. Touch the beaker. Do you feel any change in temperature ? Objective – Combination reaction with heat change. Inference – Calcium oxide (CaO) reacts vigorously with water and form a single product, calcium hydroxide (slaked lime). CaO(s) + H2O …

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IN A CHEMICAL REACTION, ORIGINAL SUBSTANCE LOSES ITS NATURE AND IDENTITY

Objective– To understand a chemical reaction. Procedure – Take a magnesium ribbon. Clean it by rubbing with sand paper. (a) Why should magnesium ribbon be cleaned before burning in air ? Hold it with a pair of tongs. Burn it in the flame of a burner. Collect the ash so formed in a watch glass. Precaution …

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How to solve Problems based on Law of Definite Proportions / Constant Composition

Read first – What is Matter? What is its Characteristics? States of Matter Law of Conservation of Mass Problems based on Law of Conservation of Mass Law of Definite Proportions / Constant Composition Mole Concept – Importance and formulas Problem 1 : One mole of  V2O5 contains 5 moles of oxygen atoms, as it is clear from …

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A CHEMICAL REACTION IS CHARACTERIZED BY FORMATION OF A PRECIPITATE.

When a chemical reaction occurs, following observations help us to determine whether a chemical reaction has taken place. (1) Formation of a precipitate (2) Change in colour (3) Evolution of a gas (4) Change in state (5) Change in temperature or evolution / absorption of heat (6) Sound, light may be produced. (7) Change in …

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