Where.. <span>[At] = concentration of component "A" after time = t has elapsed </span> <span>k = rate constant </span> <span>t = time elapsed </span> <span>[Ao] = concentration at time = 0.. i.e.. the concentration you started with. </span>
<span>************ </span> <span>now... you have pressure.. not concentration right? </span>
<span>if your gas is an ideal gas, then </span> <span>PV = nRT </span> <span>P = (n/V) x (RT) </span>
<span>and since "concentration" = moles / volume.. i.e.. [A] = n/v </span> <span>and since "R" is a constant </span> <span>and since "T" is a constant </span>
<span>[A] = P / (RT) </span>
<span>***** </span> <span>so we can either do this.. </span> <span>ln( Pt/(RT) ) = -kt + ln( Po/(RT)) </span>
<span>and since Pt and "t" vary and Po and R and T are constant </span>
<span>this is of the form </span> <span>y = mx + b </span>
<span>if we let </span> <span>.. y = ln( Pt / (RT) ) </span> <span>.. m = -k </span> <span>.. .x = time </span> <span>.. b = ln( Po / (RT)) </span>
<span>i.e.. a plot of ln(P / RT) on the y-axis versus time on the x-axis will have a slope = -k </span>
<span>so.. </span> <span>open up an excel spreadsheet </span> <span>make three columns starting with T = </span>
<span>mouse to A2 </span> <span>left click and hold </span> <span>drag highlight to A7 </span> <span>press and hold ctrl </span> <span>release mouse (keep holding ctrl </span> <span>mouse to c2 </span> <span>left click and hold </span> <span>drag to c7 </span> <span>release ctrl </span> <span>release mouse </span> <span>left click insert </span> <span>left click scatter </span> <span>choose the upper left one with just the data points by left clicking on it </span> <span>right click on any data point on the plot </span> <span>left click add trendline </span> <span>left click the two boxes to display equation on chart and display r^2 </span> <span>close </span> <span>right click on the equation that appeared on the plot </span> <span>left click format trendline label </span> <span>sent number format to display 8 decimal points </span>
<span>and... TADA.. you have.. </span> <span>(1).. plotted ln(P/RT) vs time </span> <span>(2).. fitted the data points with the equation y = -0.00020775x - 4.0986 </span>
