Q1. What is a redox reaction?
Q2. What is corrosion? Explain its advantage anddisadvantage.
Q3. What is rancidity? How can we reduce theproblem of rancidity?
Q4. How is corrosion different from rusting?
Q5. What is meant by endothermic and exothermic reactions? Give suitable example for each.
Q6. Define different types of chemical reaction andgive examples for each.
Q7. Why is photosynthesis considered as anendothermic reaction?
Q8. In electrolysis of water, why is the volume of gas collected over one electrode double that of the
other electrode?
Q9. What happens when water is added to solidcalcium oxide taken in a container? Write achemical formula for the same.
Q10. Give one use of quick lime.
Q11. Give three types of decomposition reaction.
Q12. Name the compound used for testing CO²gas.
Answers
Answer:
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1 ) Redox reactions are reactions in which one species is reduced and another is oxidized. Therefore the oxidation state of the species involved must change.
2 ) Protection : Surface corrosion forms an oxide layer which further protects the inner metal form corrosion. Corrosion prevents corrosion : Some metals like zinc are used as sacrificial anodes to prevent corrosion to other metal. ... The main disadvantages of corrosion of metal are: Lose of metal from the surface.
3 ) The condition produced by aerial oxidation of fats and oils in foods marked by unpleasant smell and taste is called rancidity. Rancidity can be prevented by adding anti -oxidants to foods containing fats and oils. 2. Rancidity can be prevented by packaging fats and oil containing foods in nitrogen gas.
4 ) Corrosion is the process of deterioration of materials as a result of chemical, electrochemical or other reactions. Rusting is a part of corrosion and is a chemical process which results in the formation of red or orange coating on the surface of metals. Rust or rusting can affect only iron and its alloys.
5 ) reaction in which heat energy is liberated by the reactants is called exothermic reaction. eg: Carbon + Oxygen gives Carbon Dioxide + Q. reaction in which heat energy is absorbed by the reactants is called endothermic reaction. eg: Nitrogen + Oxygen gives 2 nitrous oxide (2NO) - Q.
6 ) The five basic types of chemical reactions are combination, decomposition, single-replacement, double-replacement, and combustion. Analyzing the reactants and products of a given reaction will allow you to place it into one of these categories. Some reactions will fit into more than one category.
7 ) Photosynthesis is considered an endothermic reaction, because during the process of photosynthesis, energy from the sun or sunlight is being absorbed. Any chemical reactions that absorb heat energy from the surroundings to form products is termed the endothermic reaction.
8 ) Water composition is 2atoms of H and 1atom of O . Therefore H is double than O . The two electrodes collect H and O separately . We know that hydrogen composition in water is double than oxygen , so we find volume of gas collected in one electrode is double than volume of gas collected in another electrade
9 )When calcium oxide is added to water it forms calciun hydroxide Called slaked lime. CaO +H2O →Ca(OH)2 The reaction between water and CaO is an exothermic reaction. Heat is released during exothermic reaction ,rise in temperature is observed.
10 ) Uses: Quicklime has a wide range of uses, including in the production of iron and steel, paper and pulp production, treatment of water and flue gases and in the mining industry. For the iron and steel industry, we also supply different fractions of both reactive shaft furnace-burnt and hard-burnt rotary kiln lime.
11 ) Decomposition reactions can be classified into three types:
Thermal decomposition reaction.
Electrolytic decomposition reaction.
Photo decomposition reaction.
12 ) Calcium hydroxide solution ( freshly prepared), also called lime water, is used to test CO2 gas.
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