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प्रश्न
Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
Why are decomposition reactions called the opposite of combination reactions? Explain with equations of these reactions.
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उत्तर
Decomposition reactions occur when a compound breaks up into two or more simpler substances. On the other hand, combination reactions occur when two or more substances combine to form a single substance. Thus, decomposition reactions are the opposite of combination reactions.
Decomposition Reactions:
\[\ce{CaCO3_{(s)} -> CaO_{(s)} + CO2_{(g)}}\]
\[\ce{2H2O_{(l)} ->[Electricity] 2H2_{(g)} + O2_{(g)}}\]
Combination Reactions:
\[\ce{2H2_{(g)} + O2_{(g)} -> 2H2O_{(l)}}\]
\[\ce{NH3_{(g)} + HCl_{(g)} -> NH4Cl_{(s)}}\]
संबंधित प्रश्न
Why is the amount of gas collected in one of the test tubes in the following Activity double of the amount collected in the other? Name this gas.
- Take a plastic mug. Drill two holes at its base and fit rubber stoppers in these holes. Insert carbon electrodes in these rubber stoppers as shown in the following Fig.
- Connect these electrodes to a 6 volt battery.
- Fill the mug with water such that the electrodes are immersed. Add a few drops of dilute sulphuric acid to the water.
- Take two test tubes filled with water and invert them over the two carbon electrodes.
- Switch on the current and leave the apparatus undisturbed for some time.
- You will observe the formation of bubbles at both the electrodes. These bubbles displace water in the test tubes.
- Is the volume of the gas collected the same in both the test tubes?
• Once the test tubes are filled with the respective gases, remove them carefully. - Test these gases one by one by bringing a burning candle close to the mouth of the test tubes.
Caution: This step must be performed carefully by the teacher.
- What happens in each case?
- Which gas is present in each test tube?
What type of reaction is represented by the digestion of food in our body?
Give one example of a decomposition reaction which is carried out with electricity.
What type of chemical reaction is used to extract metals from their naturally occurring compounds like oxides or chlorides?
Name the product formed on strongly heating ferrous sulphate crystals. What type of chemical reaction occurs in this change?
State the change in colour observed in the following case, mentioning the reason:
Silver chloride is exposed to sunlight.
Two metals X and Y form the salts XSO4 and Y2SO4, respectively. The solution of salt XSO4 is blue in colour whereas that of Y2SO4 is colourless. When barium chloride solution is added to XSO4 solution, then a white precipitate Z is formed along with a salt which turns the solution green. And when barium chloride solution is added to Y2SO4 solution, then the same white precipitate Z is formed along with colourless common salt solution.
- What could the metals X and Y be?
- Write the name and formula of salt XSO4.
- Write the name and formula of salt Y2SO4.
- What is the name and formula of white precipitate Z?
- Write the name and formula of the salt which turns the solution green in the first case.
A metal salt MX when exposed to light splits up to form metal M and a gas X2. Metal M is used in making ornaments whereas gas X2 is used in making bleaching powder. The salt MX is itself used in black and white photography.
- What do you think metal M is?
- What could be gas X2?
- Name the metal salt MX.
- Name any two salt solutions which on mixing together can produce a precipitate of salt MX.
- What type of chemical reaction takes place when salt MX is exposed to light? Write the equation of the reaction.
What are thermal decomposition reactions ? Explain with an example.
Give a scientific reason.
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Classify the following reaction into different type:
\[\ce{2KClO3(s)->[\Delta] 2KCl(aq) + 3O2(g)}\]
Give a balanced equation for –
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Give a balanced equation for –
A white precipitate obtained during a double decomposition reaction involving a silver salt with sodium salt.
Differentiate between the following:
Thermal decomposition and thermal dissociation.
Chemical volcano is an example of ______ type of reaction.
Marble statues are corroded or stained rain water. Identify the main reason.
- Identify the gasses evolved at the anode and cathode in the above experimental set up.
- Name the process that occurs. Why is it called so?
- Illustrate the reaction of the process with the help of a chemical equation.
