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sec M 0 0.0258 0.2 0.0207 0.4 0.0168 0.6 0.0134 0.8 0.0102 1 0.0084 1.2 0.0068 1

ID: 1058445 • Letter: S

Question

sec       M
0    0.0258
0.2 0.0207
0.4 0.0168
0.6 0.0134
0.8 0.0102
1   0.0084
1.2 0.0068
1.4 0.0056
1.6 0.0039
1.8 0.0042
2     0.0020
2.2 0.0026
2.4 0.0013
2.6 0.0021
2.8 0.0010
3     0.0007

which was obtained for a reaction A P.

The first column contains time in seconds and the second column the concentration of reactant in molar units

The order of the reaction is in 1st order.

1) What is the rate constant of the reaction? Be sure you include units. Use "M" for molar and "s" for seconds

2) What is the rate of the reaction at t = 0.5s? Express your answer in units of M/s

3) What is the concentration of product at t = 0.5s?

Explanation / Answer

for a 1st order reaction , -rA=-dCA/dt = KCA

K= rate constant when integrated lnCA= lnCAO-Kt

where CA = concentration at any time, t and CAO= initial concenntration

so a plot of lnCA vs t gives the slope -K and intercept of ln CAO. the plot is shown below

the rate const K= 1.146/sec

the expression ln CA= -1.146t-3.633

CA= 0.0264*e(-1.146t) , dCA/dt= rate = -0.0264*exp(-1.146t)*1.146 at t=0.5s, rate = -0.017058M/s

at t=0.5 SS, lnCA= -1.146*0.5-3.633, CA=0.0149M