alkenes

Question 1

why are alkenes also called olefins

Answer 1

alkenes are also called olefins because the lower members of alkenes form oily products when treated with chlorine and bromine

Question 2

what is alkenes general formula

Answer 2

CnH2n

where n = number of carbon atoms

Question 3

how are alkenes collected and why

Answer 3

downward displacement of water because

• –> insoluble in water
• —> inflammable gas

Question 4

what are 3 physical properties of ethene

Answer 4

• –> colourless gas having a faint sweet smell
• –> sparingly soluble in water and soluble in organic solvents
• –> vapour density is 14
• —> lighter than air

Question 5

3 uses of ethene

Answer 5

• -> used in artificial ripening of fruits
• –> used in the manufacture of ethyl alcohol
• –> used in the preparation of polythene

Question 6

which decolorize bromine solution in carbon tetrachloride

Answer 6

ethene

Question 7

____ and _____ are prepared by cracking petroleum

Answer 7

ethylene and propylene

Question 8

what is Markownikoff’s rule

Answer 8

during the addition of halogen acids to unsymmetrical alkenes,

the negative part of the reagent goes to the carbon atom with a lesser number of the hydrogen atom

positive part to other carbon atoms

Question 9

a hydrocarbon which on catalytic hydrogenation gives a saturated hydrocarbon

Answer 9

ethene

Question 10

give a chemical test to distinguish between ethane and ethene gas

Answer 10

ethene gas decolourizes the purple color of the alkaline potassium permanganate solution

while ethane gas does not

Question 11

what type of reaction does ethene undergo

Answer 11

addition reaction as it is an unsaturated hydrocarbon

Question 12

the melting point of alkenes increases with ____________ in molecular weight

Answer 12

INCREASE

Question 13

which gas is used in making household plastic material

Answer 13

ethylene / ethene

Question 14

gas used in ripening fruits

Answer 14

ethylene / ethene