Chemical reactions & equations for 10th Board exam | Edu D Study


chemical reaction
Chemical reactions and equations

The lime water turns milky when the gas arises on heating limestone is passed through freshly prepared lime water. Give reason.

  1. Calcium oxide and carbon dioxide generate when limestone is heated. 
  2. Carbon dioxide gas is passed through lime water, insoluble calcium carbonate, and water is found and lime water turns milky in this reaction.

Ca(OH)2 + Co2 --------> Caco3 + H2O

For storing oil for a long time, it is recommended to use an airtight container. Give reason.


  1. If edible oil is allowed to stand for a long time, it undergoes oxidation. It becomes rancid. Its smell and taste also change.
  2. Rancidity in foodstuff of cooking oil or ghee is prevented by using antioxidants. The process of oxidation reaction of foodstuff can also be slowed down by storing it in an airtight container.

HCL powder disappears rapidly but it takes time for pieces of Shahabadi tiles to vanishes in the chemical reaction. Give reason.

  1. The rate of a reaction is determined by the size of the particles of the reactants taking part in the chemical reaction. The smaller the size of the reactant's particles, the more will be the total surface area and the faster will be the rate of reaction.
  2. CO2 effervescence is formed in the reaction of dilute HCl with pieces of Shahabad tile, and the tile disappears slowly. 
  3. On the other hand, CO2 effervescence is arisen at a faster speed with Shahabad tile powder and vanishes rapidly.

The concentrated sulphuric acid is added slowly to water with constant stirring while preparing dilute sulphuric acid from concentrated sulphuric acid in the laboratory. Give reason.

  1. The preparation of dilute sulphuric acid goes down in the category of extreme exothermic process.
  2. The amount of water is taken in a glass container which is surrounded by ice and cool for 20 minutes during the preparation of dilute sulphuric acid. 
  3. The small quantity of concentrated H2SO4 is added slowly with stirring. In this way, dilute sulphuric acid is produced.
  4. On the other hand, a  very large amount of heat is generated in the process of dilution of concentrated sulphuric acid with water. 
  5. Water gets evaporated instantaneously if it is poured into concentrated H2SO4 which may cause an accident.

What do you call when oxidation and reduction reactions occur simultaneously? Explain with one example.

  • Oxidation and a reduction reaction that occurs simultaneously in a chemical reaction are called an oxidation-reduction or redox reaction.
  • In a redox reaction, one reactant gets oxidized while the other gets reduced during a reaction.
Redox reaction = reduction + oxidation.
  • The reductant is oxidized by the oxidant and the oxidant is reduced by the reductant in a redox reaction.
For example,
CuO + H2 -----------> Cu + H2O
  • In this reaction, oxygen is detached from copper oxide. Therefore, it is the reduction of CuO while hydrogen gains oxygen to form water that means oxidation of hydrogen occurs. Hence, oxidation and reduction take place simultaneously.
Redox Reaction:
2H2S + SO2 ----------> 3S + 2H2O
MnO2 + 4HCL ------------> MnCl2 + 2H2O + Cl2

How to increase the rate of decomposition of Hydrogen Peroxide (H2O2).

  1. The decomposition of hydrogen peroxide (H2O2) into water and oxygen takes place slowly at room temperature. 
  2. However, the same reaction occurs at a faster rate on adding manganese dioxide powder (MnO2) to it.

What is mean by reactant & product giving examples?

  1. While taking part in a chemical reaction, the substance undergoes bond-breaking is called reactant.
  2. As a result of a chemical reaction, the substance is formed by the formation of new bonds is called a product.
For example,
  • In a chemical reaction, the formation of CO2 gas takes place by the combustion of coal in the air. In this reaction coal (C) and Oxygene (O) are reactants while CO2 is the product.

What are the similarity and differences between NaOH to water and CaO to water?

 Similarity

  1. Both NaOH and CaO, both dissolved separately in water, solid NaOH dissolve and releasing heat, resulting in rising in temperature. This reaction is an exothermic reaction.
  2. When solid CaO dissolves in water, Ca(OH)2 is formed and a large amount of heat is formed, and a large amount of heat is evolved. This reaction is also an exothermic reaction.
  3. Both reactions are combination reactions and a single product is obtained.

NaOH (s) + H2O  ----------> NaOH(aq) + Heat

CaO (s) + H2O    --------->    CaOH(aq) + Heat

 Differences

  1. Aquarius solution of NaOH is considered as a strong alkali
  2. Aquarius solution of Ca(OH)2 is considered weak alkali.

 

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