Question

The following data were made with the initial concentration of 0.0035 moles of hydrogen peroxide. Find the rate constant.

Moles of Oxygen          Time in minutes

0.0000656                     0.009

0.0003398                     1.839

0.0007318                     4.026

0.0010161                    7.452

Answer 1

The reaction is H2O2---> H2O +1/2O2 so 1 mole of Oxygen requires 2 mole of H2O2. So moles of O2 will be converted into moles of H2O2 consumed. Then calculate the conversion , XA= 1-moles of H2O2 present/ moles of H2O2 initially present

the slope of -ln(1-XA) vs t for a first order reaction ( The decompsition of H2O2 is first order which is verified subsequently)

the calculation and the plot are shown and the slope of the plot gives K, rate constat as 8.256min-1

Initial concentration of oxygen	0.0035	moles
Mole of Oxygen	time (minutes)	Mole of H2O2 required	mole of H2O2 present	Conversion, XA
0.0000656	0.009	0.0001312	0.0033688	0.037485714
0.0003398	1.839	0.0006796	0.0028204	0.194171429
0.0007318	4.026	0.0014636	0.0020364	0.418171429
0.0010161	7.452	0.0020322	0.0014678	0.580628571
1-XA	(-ln(1-XA)	t(min)
0.962514286	0.038206371	0.009
0.805828571	0.21588425	1.839
0.581828571	0.541579425	4.026
0.419371429	0.868998287	7.452