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Topic: Halogenations reactions  (Read 1059 times)

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Offline Fish200398

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Halogenations reactions
« on: February 25, 2020, 01:44:20 PM »
Given : A sufficient amount of chlorine (Cl2) underwent an addition reaction with a certain
amount of alkene A. The mass of the product was 140 g heavier than that of A. Then a
sufficient amount of bromine (Br2) underwent addition to the same amount of A. The mass of
the product was 460 g. Whats the correct one as the number of
carbon atoms of A.
Given also :
Mr Cl2 = 35 g
Mr Br = 80
Key answer : 5

The product was 140 g heavier than that of A. But mass of Cl2 is 70 g, what does it mean?

Offline chenbeier

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Re: Halogenations reactions
« Reply #1 on: February 25, 2020, 02:22:26 PM »
That means 2 mol Cl2 was added.

Offline Fish200398

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Re: Halogenations reactions
« Reply #2 on: February 25, 2020, 02:47:04 PM »
Oh yes, thats makes sense

Offline chenbeier

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Re: Halogenations reactions
« Reply #3 on: February 25, 2020, 02:59:21 PM »
So now calculate further. What does it mean how many mol bromine. What mass was added and what is the mass of A.
From this you can calculate how much mole A and also the amount of C- atoms.

Offline Fish200398

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Re: Halogenations reactions
« Reply #4 on: February 25, 2020, 03:04:45 PM »
Yes, thanks

Offline chenbeier

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Re: Halogenations reactions
« Reply #5 on: February 25, 2020, 03:07:52 PM »
No you should post your calculation.

Offline Fish200398

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Re: Halogenations reactions
« Reply #6 on: February 25, 2020, 03:26:02 PM »
Known : 2 moles Cl2 reacted with Alkene named A, it means the Alkene reacted also 2 moles,

Because in halogenation the mole ratio of

alkene : halogen : product = 1:1:1

2 moles of A reacted with Br2, has product of 460 g

Mass of A + mass of Br2 = 460 g
Mass of A = 460 - 320 = 140 g

2 moles of A has mass of 140 g.
Mr A = 70 g/moles
Alkene A is C5H10

Offline chenbeier

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Re: Halogenations reactions
« Reply #7 on: February 25, 2020, 03:28:00 PM »
Yes correct calculation.

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