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Question
Give two examples where a chemical reaction is accompanied by a change in colour of the reactants and products on completion of the reaction.
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Solution
(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) \[\ce{\underset{\text{colourless}}{Pb[NO3]} + 2Kl->\underset{\text{yellow ppt.}}{Pbl2 v} + 2KNO3}\]
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RELATED QUESTIONS
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. What type of change is it? Explain.
Complete and balance the following chemical equations:
Ba`"CI"_2` + `"H"_2"SO"_4` `→`
(aq.) (aq.)
MATCH THE COLUMNS
| 1 . `H_2` + `CI_2` `→` 2HCI | a. displacement reaction |
| 2. `2FeCI_3`+ `H_2` `→` `2FeCI_2` +2HCI` | b. addition of an electronegative redical |
| 3. Fe + `CuSO_4` `→``FeSO_4` +Cu` | c. removal of an electronegative redical |
| 4. `2H_2O` +`4NO_2`+`O_2` `→` `4HNO_3` | d.reduction by adding hydrogen |
| 5. 3Fe +`3CI_2` `→` `2FeCI_3` | e.electrolysis of water |
| 6. `FeCI_3`+ 3NaOH `→``Fe(OH)_3``↓`+NaCI | F.double decomposition,precipitation reaction |
| 7.`2H_2O` `→` `2H_2``↑`+`O_2` | e. combination or synthesis reaction |
TRUE \ FALSE
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\[\ce{CuCO3 ->[\Delta]}\]
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- Evolution or absorption of heat
- Formation of a precipitate.
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Neutralization reaction and a precipitation reaction.
True or False. If false, give the correct answer.
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