Advertisements
Advertisements
Question
Define Electrochemical reaction
Give an example
Solution
It is a reaction which occurs with absorption of electrical energy.
\[\ce{2H2O + ->[Electricity] 2H2 + O2}\]
APPEARS IN
RELATED QUESTIONS
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.
Give one example that illustrates the following characteristics of a chemical reaction:
Change in state
Fill in the blank.
Melting of ice is a _______ change.
Fill in the blank
A change in which the substance can be brought back to its original state is called a _______ change.
When electric current is passed through acidulated water ______ of water takes place.
Define:
Photochemical reaction
Give one example
Give examples of exothermic reactions i.e. heat evolved in each of the following:
(a) reaction between a solid and a liquid
(b) reaction between two gases
Give two examples of exothermic reactions seen in everyday life.
Give a word equation for the following reaction.
Two solids which combine on heating, to give a liquid.
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 water to quicklime.
Give balanced equation for the following conversion affected by heat alone on the substance:
Copper carbonate to copper oxide
Complete the table given below.
| Heat on sodium chloride | Colour imparted to flame during flame test |
State the following reaction represent oxidation or reduction.
\[\ce{H->H+}\]
Give a balanced equation for the conversion of a soluble lead salt to an insoluble lead salt – formed as a white precipitate.
Name the solid residual product formed reaction and state its colour during – thermal decomposition of the following substance.
Calcium hydroxide.
What happens when cane sugar is strongly heated? Mention any two changes in it.
A thick coating of a paste of Plaster of Paris (POP) is applied over the bandage on a fractured bone. It becomes hard on drying to keep the fractured bone immobilised. Can the change in POP be reversed?
______ change results in the change of the substance.
Which of the following is/are true when milk changes into curd?
- Its state is changed from liquid to semi-solid.
- It changes colour.
- It changes the taste.
- The change cannot be reversed.
Choose the correct option from below:
Classify the following processes into physical or chemical changes:
(i) Beating of aluminium metal to make aluminium foil.
(ii) Digestion of food.
(iii) Cutting of a log of wood into pieces.
(iv) Burning of crackers.
A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour.
What changes do you expect?
