Advertisements
Advertisements
प्रश्न
Give a scientific reason.
When the gas formed on heating limestone is passed through freshly prepared lime water, the lime water turns milky.
Advertisements
उत्तर
- When limestone is heated, calcium oxide and carbon dioxide gas are formed.
\[\ce{\underset{\text{carbonate}}{\underset{\text{Calcium}}{CaCO_{3(s)}}} + Heat -> \underset{\text{oxide}}{\underset{\text{Calcium}}{CaO_{(s)}}} + \underset{\text{dioxide}}{\underset{\text{Carbon}}{CO2\uparrow}}}\] - When carbon dioxide gas is passed through freshly prepared lime water, the solution turns milky due to the formation of calcium carbonate, which is insoluble in water.
\[\ce{\underset{\text{hydroxide}}{\underset{\text{Calcium}}{Ca(OH)2_{(aq)}}} + \underset{\text{dioxide}}{\underset{\text{Carbon}}{CO_{2(g)}}} -> \underset{\text{carbonate}}{\underset{\text{Calcium}}{CaCO_{3(s)}}} + \underset{\text{Water}}{H2O_{(l)}}}\]
APPEARS IN
संबंधित प्रश्न
Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
Write one equation for decomposition reactions where energy is supplied in the form of heat.
Taking into consideration the relationship in the first pair, complete the second pair
2H2 + O2 → 2H2O :Combination Reaction :: 2HgO → 2Hg + O2:_________
Decomposition reactions require energy either in the form of heat or light or electricity for breaking down the reactants. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light and electricity
A solid substance P which is very hard is used in the construction of many buildings, especially flooring. When substance P is heated strongly, it decomposes to form another solid Q and a gas R is given out. Solid Q reacts with water with the release of a lot of heat to form a substance S. When gas R is passed into a clear solution of substance S, then a white precipitate of substance T is formed. The substance T has the same chemical composition as starting substance P.
- What is substance P? Write its common name as well as chemical formula.
- What is substance Q?
- What is gas R?
- What is substance S? What is its clear solution known as?
- What is substance T? Name any two natural forms in which substance T occurs in nature.
The white solid compound A decomposes quite rapidly on heating in the presence of a black substance X to form a solid compound B and a gas C. When an aqueous solution of compound B is reacted with silver nitrate solution, then a white precipitate of silver chloride is obtained along with potassium nitrate solution. Gas C does not burn itself but helps burn other things.
- What is compound A?
- What is compound B?
- What is gas C?
- What do you think is the black substance X? What is its function?
- What is the general name of substances like X?
State an important use of decomposition reactions.
Give one example of a decomposition reaction which is carried out by applying heat.
What type of chemical reaction is used to extract metals from their naturally occurring compounds like oxides or chlorides?
What type of reaction is represented by the following equation?
\[\ce{CaCO3 -> CaO + CO2}\]
What type of reaction is represented by the following equation?
\[\ce{NH4Cl -> NH3 + HCl}\]
What type of chemical reaction takes place when limestone is heated?
What type of chemical reaction takes place when electricity is passed through water?
Name the product formed on strongly heating ferrous sulphate crystals. What type of chemical reaction occurs in this change?
What is meant by a decomposition reaction?
State the change in colour observed in the following case, mentioning the reason:
Silver chloride is exposed to sunlight.
Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.
\[\ce{Zn_{(s)} + H2SO4 -> ZnSO4_{(s)} + H2_{(g)}}\]
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Thermal decomposition of a substance is brought about with the help of
- reactants
- water
- wind
- heat
What does one mean by endothermic reaction? Give example.
A student wants to study a decomposition reaction by taking ferrous sulphate crystals. Write two precautions he must observe while performing the experiment.
Give a balanced equation for –
An electrolytic decomposition reaction involving a neutral liquid
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 compound decomposes to give two new compounds.
Differentiate between the following:
Thermal decomposition and thermal dissociation.
What is electrolysis?
Electrolysis is type of ______ reaction.
Chemical volcano is an example of ______ type of reaction.
The following reaction is used for the preparation of oxygen gas in the laboratory:
\[\ce{2KClO3_{(s)} ->[Heat] 2KCl + 3O2_{(g)}}\]
Which of the following statement about the reaction is correct?
Which one of the following processes involves chemical reactions?
Which of the following is an endothermic process?
Balance the following chemical equation and identify the type of chemical reaction.
`"HgO"("s") overset("(heat)")(->) "Hg"("l") + "O"_2("g")`
On heating blue coloured powder of copper (II) nitrate, in a boiling tube, copper oxide (black), oxygen gas and a brown gas X is formed
- Write a balanced chemical equation of the reaction.
- Identify the brown gas X evolved.
- Identify the type of reaction.
- What could be the pH range of aqueous solution of the gas X?
When lead nitrate is heated strongly in a boiling tube, two gases are liberated and a solid residue is left behind in the test tube.
- Name the type of chemical reaction and define it.
- Write the name and formula of the coloured gas liberated.
- Write the balanced chemical equation for the reaction.
- Name the residue left in the test tube and state the method of testing its nature (acidic/basic).
