Question

1) When 100g of ethylene polymerizes to polythene according to the equation:-
nCH2=CH2 ---->-(- CH2-CH2-)n. Then the weight of polyethylene produces will be =?

2) A hydrocarbon contain 80% C. The vapour density of compound is 30. Molecular formula is:-
i) C4H12 or ii) C2H4

Answer 1

1.

When 100g of ethylene polymerizes to polythene then the weight of polyethylene produces will be : 100g

Explaination:

This answer can be verified by Law of Conservation of Mass.

This law states that Mass can neither be created nor destroyed in any chemical reaction. Thus to obey this law, the amount of product formed will have mass equal to the amount of reactant.

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2)

GIVEN:

• Amount of Carbon = 80%
• vapour Density (VD) = 30

Need to FIND:

• Molecular formula=?

ANSWER:

VD= Molecular Mass ÷ 2

=> 30= Molecular mass÷ 2

=> Molecular Mass= 60

━━━━━━━━━━━━━━━

In 100%------- 60g C

then 80%-----(60÷100)×80 g

= 48g

=4C

━━━━━━━━━━━━━━━━

H= 60g - 48g

= 12g

=12H

━━━━━━━━━━━━━━━━━━

Thus the formula is:

i) C4H12 ( ans)

Answer 2

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