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Chemistry Nov08 paper 4! need help ASAP!

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I give the full question to make it easier for you guys-- :)
Hey guys I dont really understand Q2b ( the table part) and Q4. biii)

Question 2

In the late 19th century the two pioneers of the study of reaction kinetics, Vernon Harcourt
and William Esson, studied the rate of the reaction between hydrogen peroxide and iodide
ions in acidic solution.
H2O2 + 2I– + 2H+ 2H2O + I2
This reaction is considered to go by the following steps.
step 1 H2O2 + I– IO– + H2O
step 2 IO– + H+ HOI
step 3 HOI + H+ + I– I2 + H2O
The general form of the rate equation is as follows.

rate = k[H2O2]a[I–]b[H+]c

2(b)Suggest values for the orders a, b and c in the rate equation for each of the following
cases.
numerical value a b c
step 1 is the slowest overall
step 2 is the slowest overall
step 3 is the slowest overall

Question 4

Dont really understand ONLY question b iii) even through marking scheme. Can anyone explain to me ???

Used car engine oil can be recycled for use as a fuel by the processes of distillation and
cracking.
(i) Assuming a typical molecule of engine oil has the formula C40H82, suggest an
equation for a cracking reaction that could produce diesel fuel with the formula
C16H34 and other hydrocarbons only.

Ans: C40H82 → C16H34 + 2 C12H24 OR C24H48

(iii) Considering only the bonds broken and the bonds formed during the reaction, use
the Data Booklet to calculate the enthalpy change for the reaction you wrote in
(b)(i).

Ans: ????????????
 
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u check out p5 (a2) prac skills
it xplains it real good and if u want 2 no da ans still
pm me!
 
Messages
51
Reaction score
2
Points
18
workinghard said:
u check out p5 (a2) prac skills
it xplains it real good and if u want 2 no da ans still
pm me!

I still dont get it. Can you explain to me in details
 
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