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Explain effect of temperature on equilibrium by suitable experiment. |
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Answer» Solution :Effect of temperature on equilibrium can be demonstrated by taking `NO_2` gas (brown in colour) which dimerises into `N_2O_4`gas (colourless). `{:(2NO_(2(g))HARR, N_2O_(4(g)) , , DeltaH-57.2 "kJ mol"^(-1)),("brown"" ""colour gas","colourless gas",):}` Method of experiment : `NO_2` gas prepared by ADDITION of Cu turnings to conc. `HNO_3` is collected in two 5 mL TEST tubes (ensuring same intensity of colour of gas in each tube) and stopper sealed with araldite. Take three 250 mL beakers 1, 2 and 3. Take three 250 ml beakers 1, 2 and 3 containing freezing mixture, water at room temperature and hot water (363K) respectively. Both the test tubes are placed in BEAKER 2 for 8-10 minutes. After this one is placed in beaker 1 and the other in beaker 3. The effect of temperature on direction of reaction is depicted very well in this experiment. This is shown in following figure.  Observation: (i) At low temperature in beaker 1, the forward reaction of formation of `N_2O_4` is preferred, as reaction is exothermic, and thus, intensity of brown colour due to `NO_2` decreases. (ii) While in beaker 3, high temperature favours the reverse reaction of formation of `NO_2` and thus, the brown colour intensifies. Deduction In exothermic reaction, the temperature decreases so, forward reaction and if the temperature increases the reverse reaction occurs. |
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