I. 1 ToP the value. I for sig figs. I for units. I. As a reaction proceeds, does
ID: 574103 • Letter: I
Question
I. 1 ToP the value. I for sig figs. I for units. I. As a reaction proceeds, does the instantaneous reaction rate increase or decrease? 2. Consider the data at right for CH3OH(aq) + HCl(aq) CH3Cl(aq) + H2O( Time (min) HCI (M) : 0.0 54.0 107.0 215.0 430.0 0.580 1.85 (a) Calculate the average rate of reaction, in M/min, for the time 1.36 region 0-54 minutes. (Remember: report rate of reaction as positive, i.e. absolute value.) (b) Do the same for the time interval 54-430 minutes (c) Determine, to 2 sig figs, the instantaneous rate of ! reaction at t=107 minutes, from the slope of a tangent line. You can use the graphing area at right to plot the points, connect the points by hand with a curve, and then with a ruler draw a tangent line (recall the dashed line in class). (We won't grade o the graph, just the answer.) (d) What would the answer to (a) be in mM/sec units?Explanation / Answer
1. As a reaction proceeds, the concentration of the reactants decreases.
For example, let us take the reaction:
aA + bB -----> cC + dD
the rate of this reaction can be written as-
rA = -k[A]a[B]b
Now we can see clearly that as the concentration of the reactants decreases, the driving force of the reaction reduces and hence the reaction rate decreases.