Prep Of Ethyne Flashcards
Why would first test tube be discarded / less pure?
Oxygen present
What was observed when dilute bromine solution was added?
Brown -> Colourless
What was observed when potassium manganate was added?
Lilac -> Colourless
What information do these tests give about Ethyne?
Unsaturated
How would you confirm that Ethyne gas is flammable?
Insert lighting taper into test tube
What flame does Ethyne give off?
Sooty / Smoky
Balanced equation for the combustion of Ethyne in excess oxygen
2C2H2 + 5O2 → 4CO2+2H2O
How does the flame in welding differ?
Cleaner flame
What is observed when water is dropped onto CaC2?
Effervescence (fizzing)
Compare observations in Ethene & Ethyne tests
Ethyne - smoky/sooty flame
Ethene - cleaner flame
Name + Appearance of catalyst
CaC2 - Calcium Carbide - dark, sandy colour
Unsaturated meaning
Double or triple bond present
How to test for unsaturation
Add bromine water or acidified potassium manganate (KMnO4)
What is observed in a test for unsaturation ?
Decolorisation
Give a major use of ethyne
Welding
