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प्रश्न
With the help of an appropriate example, justify that some of the chemical reactions are determined by a change in temperature.
Give a chemical equation for the reaction involved in the above case.
Give one example of a chemical reaction characterised by a change in temperature.
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उत्तर
When quicklime reacts with water, slaked lime forms with the release of a large amount of heat, causing a temperature change in the reaction mixture.
\[\ce{CaO + H2O -> Ca(OH)2 + Heat}\]
Notes
Students should refer to the answer according to their questions.
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संबंधित प्रश्न
Translate the following statement into chemical equation and then balance it.
Hydrogen gas combines with nitrogen to form ammonia
Write the balanced chemical equation for the following reaction.
\[\ce{Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water}\]
When potassium nitrate is heated, it decomposes into potassium nitrite and oxygen. Write a balanced equation for this reaction and add the state symbols of the reactants and products.
Give one example of a chemical reaction characterised by a change in state.
One of the following does not happen during a chemical reaction. This is:
(a) Breaking of old chemical bonds and formation of new chemical bonds
(b) Formation of new substances with entirely different properties
(c) Atoms of one element change into those of another element to form new products.
(d) A rearrangement of atoms takes place to form new products.
The chemical reaction between two substances is characterised by a change in colour from orange to green. These two substances are most likely to be:
(a) potassium dichromate solution and sulphur dioxide
(b) potassium permanganate solution and sulphur dioxide
(c) potassium permanganate solution and lemon juice
(d) potassium dichromate solution and carbon dioxide.
Why do we need to balance chemical equations?
Write word equation for the following skeletal equation:
\[\ce{KNO3 -> KNO2 + O2}\]
Balance the following equation. Also name the product formed.
PbCO3 → PbO +CO2
In the experiment for determining the percentage of water absorbed by raisins, we do the final weighing of the raisins after keeping them dipped in water for about one hour. For the accuracy of the result, the extra water from the surface of the soaked raisins is removed by
Write the answer to the following.
Explain the similarity and difference in two events, namely adding NaOH to water and adding CaO to water.
Balance the following equation:
\[\ce{S + HNO3 -> H2SO4 + NO2 + H2O}\]
Write the balanced chemical equation of the following reaction.
copper + nitric acid → copper nitrate + nitric oxide + water
Write the balanced chemical equation of the following reaction.
zinc sulphide + oxygen → zinc oxide + sulphur dioxide
Write the balanced chemical equation of the following reaction.
aluminium carbide + water → aluminium hydroxide + methane
Balance the following simple equation:
Mg + CO2 → MgO + C
Write a balanced equation for the following word equation:
Potassium bicarbonate → Potassium carbonate + Water + Carbon dioxide
Underline the compound in the equation given below, it is incorrectly balanced and write the correct balancing for the same.
CaC2 + N2 → 2CaCN2 + C
Dil. HCl is added to Zn granules. How will you prove that chemical change has taken place here? Support your response with two arguments.
