I need help determining the order of the reaction with respect to the hydrogen p

Question

I need help determining the order of the reaction with respect to the hydrogen peroxide degradation and both question 2 and 3.

Question 1 (4 pt) You have taken an absorbance vs time spectrum of the degradation of hydrogen peroxide (H2O2 ?H2O + ½ 02). The data points for the spectrum are provided below. First plot these data points in excel and determine the order of the reaction with respect to the hydrogen peroxide degradation. The data you will use can be found on Canvas (P7 S1 Pre-Lab data.xls) Absorbance vs Time spectrum of the degradation of hydrogen peroxide 0.3 0.25 O o.2 0.15 0.1 0.05 0 40 60 80 100 120 140 160 0 20 Time (s) Question 2 (3 pt) Determine overall order, rate, and overall rate equation for the previous reaction Question 3 (3 pt) The half-life of this reaction is the amount of time it takes for 50% of the hydrogen peroxide to react. Calculate the half-life of this system. Symbolically state the equations you are using defining all variables and constants

Explanation / Answer

The rate law for decomposition of H2O2 is:

Rate=k [H2O2]^n ,where n=order of rxn with respect to H2O2

As H2O2 is the absorbing species, so the concentration change of H2O2 can be estimated spectrophotometrically.

Abs=C(H2O2)* e*l ,

where C(H2O2)=concentration of H2O2, e= molar absorptivity of H2O2, l=path length of light

So, Absorbance is proportional to the C(H2O2)

2) The plot of [Abs ] vs time is exponential,so, the rxn is first order with respet to H2O2,

C(H2O2)=C(H2O2)o exp(-kt)

where C(H2O2)=concentration of H2O2 at time t

C(H2O2)o=concentration of H2O2 at time t=0

k=rate constant

3) given t1/2=half-life for H2O2 degradation

from the equation of first order, C(H2O2)=C(H2O2)o exp(-kt)

ln(C(H2O2)/C(H2O2)o =-kt

At t1/2,   (C(H2O2)/C(H2O2)o=1/2

So. ln(1/2)=kt1/2

or 2.303log 2=kt1/2

or 0.693/k=t1/2

So k=rate constant needs to be calculated first

from the plot of Abs vs time,

At t=0 ,Abs=0.255

At t=50 s,Abs=0.1

putting this value in the above eqn,

ln(C(H2O2)/C(H2O2)o =-kt

or, ln(0.1/0.255)=-k*50s

or k=0.0187

so t1/2=half life=0.693/0.0187=37.059 s=37.0s

t1/2=37.0s

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