[BLANK_AUDIO]. So now you should have done all your calculations and determined the order and the rate constant. Just, let's just have a look at how the calculations should've been done. So, the first that you should've done is you should've worked out your constant of proportionality, in order to be able to determine concentration. So the constant of proportionality c, was the initial concentration of hydrogen peroxide divided by the final volume of oxygen evolved, so that would be 0.892 moles per liter. That's the initial concentration hydrogen peroxide divided by 35.1 centimeters cubed, the final volume of oxygen evolved. And that gives you a value of the constant of proportionality as 0.0254 moles per liter per centimeter cubed. Okay so now we have that value we can convert our volumes into concentrations. So here's our data set, here are the times, the times that you will have measured. And then the times which I gave you. The volumes liberated which you would have measured and the ones that I gave you later on. So, we want to convert these volumes into concentrations of hydrogen peroxide at a given time. We need to take c times the final volume minus the volume at time t, that's the value in this second column here. So, at the initial time t equals 0, the concentration will be 0.892 moles per liter and that's what we expect. And that's what we had over here as our initial concentration of hydrogen peroxide. Then as time proceeds, the concentration hydrogen peroxide falls until after half an hour. It's right the way down to 0.051 moles per liter. So let's start with our zero order plot which is quite straightforward. So we're going to just take the hydrogen peroxide concentration which we had from table on the previous slide against time. And to make a plot where the hydrogen hydrogen peroxide concentration is on the y axis and time is on the x axis. We can see immediately that this plot is not linear. You can also see the importance of this point out here at about, round about half an hour. Because if we're just taking some points over a few minutes of reaction, we probably could have said that this was more or less linear. But you can see as time progresses, this is certainly not a linear plot. And so we can exclude the possibility of zero order kinetics. Now for first order, what we're going to plot now is the logarithm, natural logarithm of the concentration of hydrogen peroxide versus times. So, this column here, I've taken the natural logarithm. You can see all the numbers are negative. That's because the concentration of hydrogen peroxide is always less than one mole per liter. And if we make that plot now, where we've got the natural log on the y axis and time in seconds on the x axis. We can see we have really a very, very nice straight plot, linear plot. And consequently this would be a strong indication that this reaction is showing first-order kinetics. Finally, we'll make a second order plot. So for this now, we need to take 1 over the concentration of hydrogen peroxide. It's a function of time, so that's what I have done in this column here. And if we now make the plot we've got 1 over concentration of hydrogen plot on the y axis versus time in seconds on the x axis. And again we can see that the plot is non-linear again that we can also see that the importance of this point out here at half an hour. Because for, again for short periods of time we could have imagined that this could have been a linear plot. So we can say certainly that this is not Second Order Kinetics. So we excluded Zero in Second Order. We've got a strong indication that is, showing at least Pseudo First Order Kinetics. So having established that the order of the Kinetics is First Order, we can go back to our First Order Linear Plot. And from that we can determine the slope, the slope is negative of minus 1.609 times 10 to the minus 3 in units of per second. And from that we can get the apparent rate constant which is minus the slope, so the Faraday constant is 1.609 times 10 to the minus 3 per second. So, we, we've used this data from the decomposition of hydrogen peroxide. To look at the evolution of the oxygen gas, and from that we've been able to determine both the order of reaction. And also the apparent rate constant for the reaction. [BLANK_AUDIO]