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Which of the following relations represents the temperature coefficient of a reaction ?A. `r_(t+10)/r_(t)`B. `(t_(k))/(t_(t)+10)`C. `k_(t+10)/k_(t)`D. `(E_(a)-K_(t+10))/(E_(a)+K_(t))` |
Answer» Correct Answer - C The temperature coefficient of a reaction gives the number of times the rate of a reaction increases by a rise in temperature of `10^(@)C` It is expressed as ther ratio of the rate constants of a reaction at two different temperatureas (usually `35^(@)C` and `25^(@)C`) differing by `10k` . Thus Temperature coefficient `=(k_(35^(@))/(k_(25^(@)` The temperature coefficient of most of the reactions is positive and lies between `2` and `3` . A reaction whose temperature coefficient is negative is `2NO(g)+O_(2)(g)rarr2NO_(2)(g)` Thus, the rate of this reaction decreases with increases of temperature. It can be explained following: Reaction Mechanism `2NO(g)rarrN_(2)O_(2)(g)` `N_(2)O_(2)(g)rarr2NO_(2)(g)` At higher temperature more `N_(2)O_(2)` molecules are dissociated. The lower concentration of `N_(2)O_(2)` molecules at higher temperature result in decrease of reaction rate. |
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