Advertisements
Advertisements
प्रश्न
Give two examples where a chemical reaction is accompanied by a change in colour of the reactants and products on completion of the reaction.
उत्तर
(i) \[\ce{\underset{\text{magnesium}}{Mg} + \underset{\text{Blue copper sulphate}}{CuSO4} ->\underset{\text{colourless magnesium sulphate}}{MgSO4}+\underset{\text{copper}}{Cu}}\]
(ii) \[\ce{2Pb[NO3]2->\underset{\text{litharge (yellow)}}{2PbO} + 4NO2 + O2}\]
(iii) \[\ce{\underset{\text{colourless}}{Pb[NO3]} + 2Kl->\underset{\text{yellow ppt.}}{Pbl2 v} + 2KNO3}\]
APPEARS IN
संबंधित प्रश्न
The gas we use in the kitchen is called liquefied petroleum gas (LPG). In the cylinder, it exists as a liquid. When it comes out from the cylinder it becomes a gas (Change − A), then it burns (Change − B). The following statements pertain to these changes. Choose the correct one.
How do the following help in bringing about a chemical change?
pressure.
Complete and balance the following chemical equations
NaCI + `AgNO_3` `→`
Write the missing reactants and products and balance the equations.
\[\ce{KClO3 ->[heat]}\] ___________+ ____________
Fill in the blank:
In some chemical reactions an insoluble ________ is formed when two solutions are mixed.
Balancing a chemical equation is based on
Give reason for the following:
Molybdenum is used in the manufacture of ammonia.
What is observed in performing the following :
| Hydrogen | Oxygen | Carbon dioxide | Chlorine | |
| Litmus test | ||||
| Apply a burning splint to the gas | ||||
| Colour of gas | colourless | colourless | colourless | greenish-yellow |
| Odour of gas |
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- Formation of a precipitate.
With reference to each of the above indications, state the external indication seen during – Addition of dilute hydrochloric acid to silver nitrate.
Give balanced equation for the following conversion affected by heat alone on the substance:
Hydrated copper sulphate to sulphur dioxide
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Copper nitrate.
What happens when cane sugar is strongly heated? Mention any two changes in it.
Mention the various conditions required for a chemical reaction to occur.
Discuss how acid rain occurs due to emission of smoke from vehicles and industries?
Which of the following is not an “element + element → compound” type reaction?
The chemical name of baking soda is sodium bicarbonate.
Which is used as a catalyst during the process of hydrogenation of oils?
Give an example where heat, light, and sound are produced during a chemical change.
Why is spoiling food a chemical change?
When milk is mixed with coffee decoction, the colour of milk and decoction changes due to ______.
