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ChemistryClass 10ICSE

Explain the following in terms of gain or loss of Oxygen with one example each: (i) Oxidation (ii) reduction (b) When copper powder is heated strongly in air, it forms copper oxide. Write a balanced chemical equation for this reaction. Name (i) substance oxidised, and (ii) substance reduced

(a) Oxidation is addition of oxygen and reduction is removing of oxygen H2S + Cl2→ S + 2HCl Here, hydrogen is removed from hydrogen sulphide so it is oxidation and hydrogen sulphide is oxidized to sulphur. (b) 2Cu + O2 → 2Cu0 (i) Cu is oxidized (ii) O2is reduced

ChemistryClass 10ICSE

Give one example of an oxidation-reduction reaction which is also: (a) A combination reaction A displacement reaction

2Cu + O2 → 2CuO (Heat is given) Copper combines with oxygen to form copper oxide and it is a oxidation-reduction reaction CuO + H2→ Cu + H2O Here hydrogen displaces copper to form dihydrogen oxide (Water)

ChemistryClass 10ICSE

Zinc oxide reacts with carbon, on heating, to form zinc metal and carbon monoxide. Write a balanced chemical equation for this reaction. Name (i) oxidizing agent, and (ii) reducing agent, in this reaction.

ZnO + C → Zn + CO Oxidizing agents is a reactant which gain electrons and reduced during a redox reaction and here Zinc oxide is the oxidizing agent Reducing agent or reductant is that which substance causes another substance to reduce or it loses electron and oxidized in a chemical reaction. Here carbon is reducing agent.

ChemistryClass 10ICSE

What is a decomposition reaction? Give an example of a decomposition reaction. Describe an activity to illustrate such a reaction by heating.

Decomposition reaction is a reaction where the compounds break down or splits into two or more products. They are classified into three. Thermal decomposition, electrolytic decomposition and photo decomposition reaction There are so many examples for decomposition reactions one of them is decomposition of calcium carbonate into calcium oxide and carbon dioxide when heated Decomposition reaction by heating is called Thermal decomposition reaction. Here is an example for that ki

ChemistryClass 10ICSE

What is the colour of ferrous sulphate crystals? How does this colour change after heating? (b) Name the product formed on strongly heating ferrous sulphate crystals. What type of chemical reaction occurs in this change?

Ferrous sulphate crystals are green in colour and after heating it becomes white because on heating ferrous sulphate crystals loses water and anhydrous ferrous sulphate FeSO4 is formed so the colour changes from light green to white. (b) On strong heating the anhydrous sulphate decomposes to form Ferric oxide, sulphur dioxide and sulphur trioxide. This is a decomposition reaction 2FeSO4→ Fe2O3 + SO2+ SO3

ChemistryClass 10ICSE

Give an example of an endothermic reaction? (b) Is oxidation an exothermic or an endothermic reaction? Explain, by giving an example, how oxidation and reduction processed side by side.

Endothermic reaction is a reaction heat is absorbed by the reaction and example is burning of carbon in presence of oxygen gives carbon dioxide and a large amount of heat is released C (s) + O2 (g) →CO2 + Heat Oxidation is an exothermic Oxidation is areaction which oxygen combines with other elements and exothermic reaction releases energy through light or heat CuO + H2→ Cu + H2O In this above reaction, Copper oxide is

ChemistryClass 10ICSE

Define a combination reaction. (b) Give one example of a combination reaction which is also exothermic. Give one example of a combination reaction which is also endothermic.

Combination reactions are those reactions in which two or more substances combine to form a single substance or product or two reactants combine to form one product C (s) + O2 (g) →CO2 + Heat (Burning of carbon in presence of oxygen to produce carbon dioxide) N2 (g) + O2 (g) + Heat → 2NO (g)

ChemistryClass 10ICSE

What is a redox reaction? Explain with an example. (b) When a magnesium ribbon burns in air with a dazzling flame and forms a white ash, is magnesium oxidised or reduced? Why? (c) In the reaction represented by the equation: MnO2 + 4HCl → MnCl2 +2H2O +Cl2 (i) Name the substance oxidized (ii) Name the oxidizing agent Name the substance reduced (iv) Name the reducing agent

A redox reaction is a reaction where oxidation and reduction occurs It is also called redox reaction. SO3(aq) + MnO4(aq) → SO4(aq) + Mn Oxidation happened for SO3and reduction happened for MnO4 Magnesium is oxidised as addition of oxygen to magnesium takes place leading to formation of magnesium oxide. (i) HCl (ii) MnO2(iii) MnO2 (iv) HCl

ChemistryClass 10ICSE

What is an oxidation reaction? Identify in the following reaction (i) the substance oxidized, and (ii) substance reduced: ZnO + C → Zn +CO

Oxidation is the process when an atom loses its electron in a reaction. Or the addition of oxygen to a substance to increase the proportion of oxygen in its molecule and oxidation can be achieved without oxygen by the removal of hydrogen i.e. dehydrogenation. (i)Substance oxidized is C (ii) Substance reduced is ZnO

ChemistryClass 10ICSE

Fill in the following blanks with suitable words: (a) The addition of oxygen to a substance is called whereas removal of oxygen is called . (b) The addition of hydrogen to a substance is called whereas removal of hydrogen is called . Anti-oxidants are often added to fat containing foods to prevent due to oxidation

Solution: Oxidation; Reduction;

ChemistryClass 10ICSE

When SO2 gas is passed through saturated solution of H2S, the following reaction occurs: SO2 + 2H2S → 2H2O +3S In this reaction, which substance is oxidized and which one is reduced?

In this reaction the substance oxidised is H2S and the substance which got reduced is SO2

ChemistryClass 10ICSE

Identify the component oxidized in the following reaction: H2S +Cl2→ S +2HCl

H2S is oxidized in the above reaction.

ChemistryClass 10ICSE

In the following reaction between lead sulphide and hydrogen peroxide: PbS(s) + 4H2O2(aq) → PbSO4(s) +4H2O(l) (a) Which substance is reduced? Which substance is oxidized?

H2O2 PbS

ChemistryClass 10ICSE

What type of reactions are represented by the following equations? (a) CaO + CO2→ CaCO3 (b) 2Na +2H2O → 2NaOH +H2 (c) Mg + CuSO4→ MgSO4 + Cu (d) NH4NO2→ N2 +2H2O (e) CuSO4 + 2NaOH →Cu(OH)2 +Na2SO4

Combination Displacement Displacement Decomposition Double displacement reaction

ChemistryClass 10ICSE

Which of the following is a combination and which a displacement reaction. (a) Cl2 +2KI → 2KCl +I2 (b) 2K + Cl2 → 2KCl

Displacement Combination

ChemistryClass 10ICSE

Balance the following chemical equations: (a) FeSO4→ Fe2O3 + SO2 + SO3 (b) Pb(NO3)2(s) →PbO(s) + NO2(g) + O2

2FeSO4→ Fe2O3 + SO2 + SO3 2Pb(NO3)2(s) → 2PbO(s) + 4 NO2(g) + O2 Both in the presence of heat and decomposition reaction takes place

ChemistryClass 10ICSE

What type of chemical reactions is represented by the following equations? (i) A + BC → AC+ B (ii) A +B → C (iii) X → Y+ Z (iv) PQ + RS → PS + RQ (v) A2O3 + 2B → B2O3 + 2A

Displacement Combination Decomposition Double displacement Displacement

ChemistryClass 10ICSE

What type of chemical reaction stake place when: (a) A magnesium wire is burnt in air? (b) Lime-stone is heated? (c) Silver bromide is exposed to sunlight? (d) Electricity is passed through water? Ammonia and hydrogen chloride are mixed?

(a) Combination. (b) Decomposition. (c) Decomposition. (d) Decomposition. Combination.

ChemistryClass 10ICSE

What type of reactions are represented by the following equations? (i) CaCO3→ CaO + CO2 (ii) CaO + H2O → Ca(OH)2 (iii) 2FeSO4→ Fe2O3 + SO2+ SO3 (iv) NH4Cl → NH3 + HCl (v) 2Ca + O2→ 2CaO

(i) Decomposition. (ii) Combination. (iii) Decomposition. (iv) Decomposition. (v) Combination.

ChemistryClass 10ICSE

Write one equation each for the decomposition reactions where energy is supplied in the form of (a) heat, (b) light, and (c) electricity.

Decomposition reaction when heat is supplied 2Pb(NO3)2→ 2PbO + 4NO2 + O2 Decomposition reaction when light is supplied 2AgCl → 2Ag + Cl2 Decomposition reaction where electricity is supplied 2H2O→ 2H2 + O2

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