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Flashcards in Ethyne Deck (17):
1

Equation for the preparation of ethyne

CaC2 + H20 = C2H2 + Ca(OH)2

2

What is ethyne also known as?

Acetylene

3

Appearance of calcium carbide?

Grey/Brown solid

4

Why is water added drop wise?

Control rate at which ethyne is formed

5

What is observed in flask during addition of water?

Calcium carbide turns into a white powder and fizzing is noticed

6

Is this reaction exothermic or endothermic?

Exothermic - heat is being released

7

What is the purpose of copper sulfate

Ethyne is bubbled through copper sulfate to remove impurities in gas [hydrogen sulfide, ammonia and phosphine]

8

How are the impurities present in the calcium carbide

Caused by hydrolysis of trades of calcium sulfide, calcium phosphide etc present in calcium di carbide

9

What is the white substance that is formed inside the flask?

Calcium hydroxide

10

Why discard the first test tube?

Consists mainly of air that has been displaced

11

What are the three impurities present in gas

Hydrogen sulfide, phosphine and ammonia

12

Equation when bromine water added

Idk?

13

What happens when ethyne is burned

Smoky luminous flame

14

What is the soot in the flame from?

Unburned carbons

15

Balanced equation for the combustion of ethyne

2C2H2 + 5O2 = 4CO2 + 2H2O

16

Uses of ethyne?

Welding and cutting metals

17

Why can’t calcium carbide be obtained in pure state?

Usually contaminated with calcium sulfide, calcium phosphide and calcium nitrite