First Order Reactions

[Nadia Nichol]

When given a graph we were taught how to tell whether it was a first order reaction or not, if it was a straight line what was the slopes relation to k?

[Calista Miramontes]

For first order, the slope= -k ; second order slope= k ; zeroth order slope =-k

[Evonne Xu 3I]

For every graph, the slope is equal to k, except the signs flip flop. For first order, k = -slope; second order, k = slope; zeroth order, k = -slope.

[Holiday Parsons 2D]

Recall these graphs from the textbook. The only reason the second order plot is positive is, not because the concentration is increasing with time, but because the value of the denominator is decreasing with time inverse to 1. The best way to remember this is this inverse property is only felt by second order reactions. And of course we know that the 1st and 0 order reactions have decreasing concentrations over time.

[Kelli Chong [1B]]

For both first order and zero order reactions, the slope (k) is negative. Therefore, looking at a linear graph, the line should be slanted downwards. Furthermore, in the case of first order reactions, a linear graph should have a Y-axis labeled as ln[A]. If the graph is decreasing exponentially, the Y-axis is simply [A].