Advertisements
Advertisements
Question
Explain the term ‘chemical reaction’ with special reference to – ‘reactants’ and ‘products’.
Solution
A chemical reaction involves the breaking of existing bonds between atoms or groups of atoms of the reactants and leading to formation of new bonds forming new substances called the products.
APPEARS IN
RELATED QUESTIONS
State whether the following statement is true or false. In case a statement is false, write the corrected statement.
Condensation of steam is not a chemical change.
How do the following help in bringing about a chemical change?
heat.
Fill in the blank.
The formation of gas bubbles in a liquid during a reaction is called ......................
Fill in the blank
A catalyst either ................or ............... the rate of a chemical change but itself remains ............... at the end of the reaction.
What are chemical reactions?
What are biocatalysts ?
Fill in the blank
A new substance is always formed in a _______ change.
Fill in the blank
A change in which the substance can be brought back to its original state is called a _______ change.
Fill in the blank:
In some chemical reactions an insoluble ________ is formed when two solutions are mixed.
A chemical equation is a statement that describes a chemical change in terms of
Explain the following reaction with one suitable example of Displacement reaction.
Explain by writing a word equation.
Bubbles are seen on adding lemon juice to baking soda.
Define the following terms
Precipitate
Give an example of a reaction where the following are involved
Heat
Give an example of the following chemical change.
A reaction where colour change is noticed
Write the chemical reaction where the following changes are observed.
Physical state is changed
Complete and balance the following reaction:
Pb(NO3)2 + KI →
State the original colour of the following substance and colour of residue obtained after heating.
Copper carbonate
What do you observe when Cobalt chloride paper is introduced in water vapour.
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.
Match the chemical reactions in List I with the appropriate answer in List II.
List I | List II | ||
1. | \[\ce{XY⇌[heat]X + Y}\] | A: | Displacement reaction |
2. | \[\ce{XY->X + Y}\] | B: | Double decomposition |
3. | \[\ce{X+Y- + A+B^-->X+B- + A+Y-}\] | C: | Endothermic reaction |
4. | \[\ce{X + YZ->XZ + Y}\] | D: | Thermal dissociation |
5. | \[\ce{X + Y->[heat]XY -\Delta}\] | E: | Decomposition reaction |
State the following reaction represent oxidation or reduction.
\[\ce{Cu++->Cu}\]
Higher order Thinking question
Peeled and unpeeled banana does not look the same. Does that mean peeling banana is a chemical change?
A reaction between an acid and a base is called ______.
Anaerobic bacteria digest animal waste and produce biogas (Change – A). The biogas is then burnt as fuel (Change – B). The following statements pertain to these changes. Choose the correct one.
Analogy:
H2O: Water:: NaCl: ______.
Which of the following statement is incorrect for a chemical reaction?
Beating an egg to make a cake is a ______.
The chemical name of baking soda is sodium bicarbonate.
Assertion (A): Cutting paper into very small pieces is an irreversible change.
Reason (R): Physical changes are always reversible.