Graphical Method: Order and k from Slope and Intercept

Question

In a study of the gas phase decomposition of hydrogen peroxide at 400 °C

H₂O₂(g)H₂O(g) + ½ O₂(g)

the concentration of H₂O₂ was followed as a function of time.

It was found that a graph of 1/[H₂O₂] versus time in seconds gave a straight line with a slope of 0.865 M^-1 s^-1 and a y-intercept of 19.6 M^-1.

Based on this plot, the reaction is _______zerofirstsecond order in H₂O₂ and the rate constant for the reaction is ______ M^-1 s^-1.

Answer 1

Since a straight line results from a graph of 1/[H₂O₂] vs. time, this tells us that the reaction is SECOND order with respect to H2O2.

The slope of the line = k so we now know that k (rate constant) = 0.865 M^-1s^-1.

So, those are your answers.