Final answer:
To determine the reaction order from CTT graphs, plot the natural logarithm of the reactant concentration versus time for a first-order reaction, or the inverse of the concentration versus time for a second-order reaction. The linearity of the resulting plot indicates the reaction order, and the slope of this line can be used to estimate the rate constant.
Step-by-step explanation:
To work out orders from concentration-time-time (CTT) graphs in the context of chemical kinetics, one needs to analyze the reaction data graphically. For a first-order reaction, you expect to see a linear relationship when plotting the natural logarithm (ln) of the concentration of a reactant versus time. On the other hand, for a second-order reaction, a plot of 1/[Concentration] versus time should yield a straight line if the reaction follows second-order kinetics.
The procedure involves taking the concentration data of a reactant over time and creating multiple graphs, each representing a different reaction order. By comparing these graphs, it is possible to determine which one shows a linear relationship. The reaction is first order if the plot of ln[Reactant] versus time is linear. In a second-order scenario, the linearity in a plot of 1/[Reactant] versus time indicates that it's second order.
Once the order of the reaction is determined, the rate constant can also be estimated from the slope of the appropriate linear graph. For a first-order reaction, the slope is equal to the negative rate constant (-k), while for a second-order reaction, the slope gives you the rate constant (k).