(76 pts) The following data was collected for the decomposition of chlorine mono

Question

(76 pts) The following data was collected for the decomposition of chlorine monoxide into chlorine and oxygen at 25 C: Time (sec) ICIO] (M) (a) Create and attach three separate plots using this data and the integrated form of the rate 0 10 20 30 40 100 200 15.0 7.01 4.76 3.52 2.71 1.20 0.65 law for a 0th, 1st, and 2nd order reaction (b) What is the order of this decomposition reaction? (c) Determine the rate law and the rate constant (86 pts) The gas phase decomposition of 2.50 M ammonia into nitrogen and hydrogen is studied at 856°C yielding the following data: Time (sec) INHs] (M) (a) Create and attach three separate plots using this data and the integrated form of the rate 200 3 300 600 750 800 900 1000 1.85 1.65 1.05 0.74 0.65 0.40 0.26 law for a 0th, 1st, and 2nd order reaction tb) What is the ractionorder of ths scomposition raction? (c) Determine the rate law and the rate constant

Explanation / Answer

Let the rate (-r)= -dCA/dt= KCAn

Where n is order of the reaction and A is ClO2.

For zero order reaction , the integrated expression becomes ( CAO is initial concentration and CA is concentration at any time t).

CA= CAO- Kt   (1) ( So a plot of CA Vs t gives a straight line passing through origin)

For a 1st order reaction

-ln(1-XA)= Kt (2) where XA= 1-CA/CAO

Or ln CA = lnCAO- Kt ( So a plot of –ln(1-XA) vs t gives straight line whose slope is K)

For a second order reaction

1/CA= 1/CAO+ Kt (3) ( the plot of 1/CA Vs t gives a straight line whose slope is K).

All the three equations are plotted and shown below

Zero order reaction plot

1st order reaction plot

2nd order reaction plot

This suggets the decomposition of Cl2O is second order .

The slope gives the rate constant whose value is 0.007/M2.sec

The rate law is -r = 0.007 [ClO2]2

2.

Let the rate (-r)= -dCA/dt= KCAn

Where n is order of the reaction and A is NH3.

For zero order reaction , the integrated expression becomes ( CAO is initial concentration and CA is concentration at any time t).

CA= CAO- Kt   (1) ( So a plot of CA Vs t gives a straight line passing through origin)

For a 1st order reaction

-ln(1-XA)= Kt (2) where XA= 1-CA/CAO

Or ln CA = lnCAO- Kt ( So a plot of –ln(1-XA) vs t gives straight line whose slope is K)

For a second order reaction

1/CA= 1/CAO+ Kt (3) ( the plot of 1/CA Vs t gives a straight line whose slope is K).

The plots for the data on decomposition of NH3 for all the three orders are shown below

1st order

The reaction is zero order with rate constant 0.002 M/sec. The rate law -r =0.002

1st order reaction plot

2nd order reaction plot

So the reaction w.r.t ClO2 is 2nd order while the reaction w.r.t. NH3 is Zero order.

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