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प्रश्न
What does one mean by endothermic reaction? Give example.
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उत्तर १
Reactions in which energy is absorbed are known as endothermic reactions.
Example: \[\ce{N2(g) + O2(g) + Heat -> 2NO(g)}\]
\[\ce{2NH3(g) + Heat -> N2(g) + 3H2(g)}\]
उत्तर २
A reaction in which heat is absorbed is called an endothermic reaction.
Example: When silver chloride is left in the sunlight, it absorbs heat and turns grey because of the formation of silver metal.
\[\ce{2AgCl(s)->[Sunlight] 2Ag(s) + Cl2(g)}\]
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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?
Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
Taking into consideration the relationship in the first pair, complete the second pair
2H2 + O2 → 2H2O :Combination Reaction :: 2HgO → 2Hg + O2:_________
Give one example of a decomposition reaction which is carried out by applying heat.
Give one example of a decomposition reaction which is carried out with electricity.
What type of chemical reaction is represented by the following equation?
X → Y + Z
What type of reaction is represented by the following equation?
NH4NO2 → N2 + 2H2O
What is the colour of ferrous sulphate crystals? How does this colour change after heating?
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\[\ce{Zn_{(s)} + H2SO4 -> ZnSO4_{(s)} + H2_{(g)}}\]
Explain the following type of chemical reaction, giving two examples for it:
Decomposition reaction
Answer the following question.
2 g of silver chloride is taken in a china dish and the china dish is placed in sunlight for some time. What will be your observation in this case? Write the chemical reaction involved in the form of a balanced chemical equation. Identify the type of chemical reaction.
Give a balanced equation for –
A double decomposition neutralization reaction involving an acid and a base
Give a balanced equation for the following type of reaction:
A thermal decomposition reaction in which a metallic nitrate decomposes to give – a basic oxide.
What is electrolysis?
Give the ratio in which hydrogen and oxygen are present in water by volume.
These consist of two statements – Assertion (A) and Reason (R). Answer these questions selecting the appropriate option given below:
Assertion: Silver bromide decomposition is used in black and white photography.
Reason: Light provides energy for this exothermic reaction.
A metal nitrate 'A' on heating gives a metal oxide along with evolution of a brown coloured gas 'B' and a colourless gas, which helps in burning. Aqueous solution of 'A' when reacted with potassium iodide forms a yellow precipitate.
- Identify 'A' and 'B'
- Name the types of the reactions involved in the above statement.
