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Unformatted text preview: reaction. Rate = k[ NH 3 ] = k k = -[ NH 3 ] = 4.12E-6 M s-1 t Note: The fact that the rate of the reaction is constant is consistent with the the half life decreasing with decreasing concentration. Less must react, so it takes less time. Average (1/[ NH 4 NCO ]) / t from t = 152 min to t = 455 min : 1 = 1 1 = 2.915 M-1 [ NH 4 NCO ] 0.171 M 0.341 M (1/[ NH 4 NCO ]) = 2.915 M-1 = 9.62E-3 M-1 min-1 t ( 455- 152 ) min (3) For a second order reaction of the form NH 4 NCO products, a plot of 1/[ NH 4 NCO ] versus t is linear with a slope equal to the rate constant, k. The slope is also expressed as (1/ [ NH 4 NCO ]) / t. Therefore, a change in the reciprocal of the concentration with time is constant. Here it is seen that (1/[ NH 4 NCO ]) / t is essentially constant with an average value of 9.63E-3 M min-1 . Therefore, the reaction is second order in NH 4 NCO , with a rate constant of 9.63E-3 M-1 min-1 ....
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