| a.What is the reaction called when oxidation and reduction take place simultaneously? Explain with one example. |
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| →The reaction in which oxidation and reduction takes place simultaneously is called as redox (or oxidation-reduction) reaction. In a redox reaction, one reactant gets oxidised while the other reactant gets reduced. The substance that brings about reduction is called a reductant or a reducing agent while the substance that brings about oxidation is called an oxidant, or an oxidising agent. Redox Reaction = Reduction + Oxidation CuO (s) + H2 (g) → Cu (s) + H2O(l) In the above reaction, copper oxide is getting reduced as oxygen is getting removed from it; while hydrogen is getting oxidised as it is accepting oxygen. 2 Marks |
| b.How can the rate of the chemical reaction, namely, decomposition of hydrogen peroxide be increased? |
| →At room temperature, the decomposition of hydrogen peroxide into water and oxygen takes place slowly. However, the rate of this reaction can be increased by adding manganese dioxide (MnO2) powder in it. Manganese dioxide acts as a catalyst.2 Marks |
| c.Explain the term reactant and product giving examples. |
| →In a chemical reaction, the substance in which the bonds are broken is known as a reactant. And the substance formed as a result of a chemical reaction by formation of new bonds is called a product. Hydrochloric acid reacts with Sodium Hydroxide to form sodium chloride and water. HCl + NaOH → NaCl + H2O e.g. Hydrochloric acid reacts with Sodium hydroxide to form sodium chloride and water. In this reaction, the bonds between H – Cl and Na – OH are broken and new bonds are formed between Na – Cl and H – OH. 2 Marks |
| d.Explain the types of reaction with reference to oxygen and hydrogen. Illustratre with examples. |
| →The three types of reactions with reference to oxygen and hydrogen are as follows: a.Combination Reaction: 2H2 + O2 → 2H2O b.Decomposition Reaction: 2H2O → 2H2 + O2 c.Redox Reaction: Redox Reaction = Reduction + Oxidation CuO (s) + H2 (g) → Cu (s) + H2O(l) 3 Marks |
| e.Explain the similarity and difference in two events, namely adding NaOH to water and adding CaO to water. |
| →Similarity: When NaOH and CaO are dissolved in water, heat is generated. Thus, both are exothermic reactions. Also, both are combination reactions. Difference: Aqueous solution of NaOH is a strong alkali while aqueous solution of CaO is a weak alkali.2 Marks |
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11 August 2019 at 23:15