Question

1. The following data were obtained as a reaction progressed and the absorption of the reactant Y was monitored. Assume the reaction is first order with respect to Y and caluclate the rate constant for this reaction graphically and determine the slope of that line, which is equal to the negative value of the rte constant.

Time (sec.)	Absorption of Y
0.0	1.410
15.0	0.324
30.0	0.075
45.0	0.017
60.0	0.004

Answer 1

Answer – We are given the absorption of the reactant Y with different time and the first with respect to Y is the first order. We know the graph of the ln[Y] Vrs time is straight line with negative slope for the first order reaction.

The negative slope = k, rate constant, so first we need to calculate the ln {Y] from the given data and calculate the rate constant as follow –

Time	Ln[Y]
0	0.343589704
15	-1.127011763
30	-2.590267165
45	-4.074541935
60	-5.521460918

From the graph we are getting the equation of straight line with negative slop is

y = -0.0979x + 0.3416

so, slop = -0.0979

so, - slope = k

so, k = 0.0979 s^-1