Advertisements
Advertisements
प्रश्न
With the help of an appropriate example, justify that some of the chemical reactions are determined by a change in colour.
Give a chemical equation for the reaction involved in the above case.
Give one example of a chemical reaction characterised by a change in colour.
Advertisements
उत्तर
When sulphur dioxide gas is passed through an acidified potassium dichromate solution, the orange colour of the potassium dichromate solution changes to green colour.
\[\ce{3SO2_{(g)} + K2Cr2O7_{(aq)} + H2SO4_{(aq)} -> K2SO4_{(aq)} + Cr2(SO4)3_{(aq)} + H2O_{(l)}}\]
Notes
Students should refer to the answer according to their questions.
APPEARS IN
संबंधित प्रश्न
Translate the following statement into a chemical equation and then balance it.
Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.
Give one example of a chemical reaction.
The chemical reaction between quicklime and water is characterised by ______.
When water is added gradually to a white solid X, a hissing sound is heard and a lot of heat is produced forming a product Y. A suspension of Y in water is applied to the walls of a house during white washing. A clear solution of Y is also used for testing carbon dioxide gas in the laboratory.
- What could be solid X? Write its chemical formula.
- What could be product Y? Write its chemical formula.
- What is the common name of the solution of Y which is used for testing carbon dioxide gas?
- Write chemical equation of the reaction which takes place on adding water to solid X.
- Which characteristic of chemical reactions is illustrated by this example?
Write word equation for the following skeletal equation:
\[\ce{Zn + HCl -> ZnCl2 + H2}\]
Balance the following equation. Also name the product formed.
`"Zn" + "HCI" → "ZnCI" _2 + "H"_2`
Balance the following equation:
S + H2SO4 → SO2 + H2O
Balance the following equation:
Zn + HNO3 `→` Zn(NO3)2 + H2O + NO2
What information does the following chemical equation convey?
Zn + H2SO4 → ZnSO4+ H2
Write the balanced chemical equation of the following reaction.
iron pyrites(FeS2) + oxygen → ferric oxide + sulphur dioxide
Identify the type of reaction taking place of the following case and write the balanced chemical equation of the reaction:
Potassium iodide reacts with lead nitrate to produce potassium nitrate and lead iodide.
A student mixes sodium sulphate powder in barium chloride powder. What change would the student observe on mixing the two powders? Justify your answer and explain how he can obtain the desired change.
Write word equation for the following molecular equation:
\[\ce{H2 [g] + Cl2 [g] ->[sunlight] 2HCl}\]
Word equation:
State which form of energy is utilised in the above chemical reaction.
A chemical reaction is generally accompanied by certain external indications or characteristics. These include – change of – (a) colour (b) state (c) smell (d) evolution of gas (e) formation of precipitate (f) evolution or absorption of heat. With reference to change of colour – state the change in colour seen when the following are heated – copper carbonate.
A chemical reaction is generally accompanied by certain external indications or characteristics. These include – change of – (a) colour (b) state (c) smell (d) evolution of gas (e) formation of precipitate (f) evolution or absorption of heat. With reference to change of colour – state the change in colour seen when the following are heated – mercury [II] oxide.
Give word equation for the following chemical reaction and give the names of the product formed.
NH3 + HCl→ NH4Cl
What is meant by ‘reactants’ and ‘products’ in a chemical equation?
What is a reactant in a chemical equation?
What are the steps involved in writing the skeletal equation?
A student took a small amount of copper oxide in a conical flask and added dilute hydrochloric acid to it with constant stirring. He observed a change in colour of the solution.
- Write the name of the compound formed and its colour.
- Write a balanced chemical equation for the reaction involved.
