Advertisements
Advertisements
Question
State four conditions necessary for a chemical reaction to take place.
Advertisements
Solution
Ans: Close contact— For a chemical reaction to take place the reactants should be brought in close contact i.e., they should be mixed,
\[\ce{Sodium + Water -> Sodium hydroxide + Water}\]
Solution form— Some substances react with each other only when they are mixed in the solution form, e.g.,
\[\ce{\underset{\text{(aq.)}}{Silver nitrate} + \underset{\text{(aq.)}}{Sodium chloride} ->\underset{\text{(ppt.)}}{Silver nitrate}+\underset{\text{(aq.)}}{Sodium nitrate}}\]
Heat— Some reactants need to be heated to undergo a chemical change, e.g.,
\[\ce{Potassium chlorate->[heat] Potassium chloride + oxygen}\]
Light— Some reactions take place in the presence of light.
\[\ce{Carbon dioxide + Water ->[chlrophyll][sunlight] Glucose + Oxygen}\]
APPEARS IN
RELATED QUESTIONS
Complete and balance the following chemical equations:
Ba`"CI"_2` + `"H"_2"SO"_4` `→`
(aq.) (aq.)
Fill in the blanK
A .............is a substance which changes the rate of a chemical reaction without undergoing a chemical change.
What are oxides ?
Define chemical reaction.
Balance the following equation :
Fe + H2O → Fe3O4 + H2
State what you would observe when the following substance is heated in a glass test tube Copper (II) carbonate Red lead .
Explain the following reaction with one suitable example of Displacement reaction.
Multiple choice:
A reaction of a type: AB + CD → AD + CD, involves
Distinguish by heating the following in dry test tubs.
Zinc carbonate, Copper carbonate and lead carbonate.
Distinguish by dilute sulphuric acid.
Copper and magnesium?
On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.
A coloured substance which leaves a black residue and evolves two gases one of which is acidic and coloured and the other neutral and colourless.
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 |
Give a balanced equation for a reaction involving the evolution of gas on the addition of dilute acid to calcium carbonate.
What happens when cane sugar is strongly heated? Mention any two changes in it.
When an aqueous solution of potassium chloride is added to an aqueous solution of silver nitrate, a white precipitate is formed. Give the chemical equation of this reaction.
Silver articles turning black: ______:: Boiling of H2O: physical change ______.
Write some materials prepared by chemical changes.
Which of the following are chemical changes?
(i) Decaying of wood
(ii) Burning of wood
(iii) Sawing of wood
(iv) Hammering of a nail into a piece of wood
Chemical changes are important in our day-to-day life. Give examples.
Write a note on the following:
Curdling of milk
