Organic Question Christmas Flashcards
What colour is phenlymethanol at room temp?
Colourless
Name a suitable apparatus to measure 1.5cm3 of phenylmethanol
Graduated syringe
How does Appearance of the oxidation of phenylmethanol change with KMnO4
Purple to brown mixture
Name a suitable technique to purify benzoic acid crystals
Recrystallisation
How would you measure the melting point of a sample of benzoic acid crystals?
Put Sample on aluminium block shown in diagram, heat slowly while observing crystals, record temperature range at which melting occurs
What was observed when a short strip of freshly sanded magnesium was added to a test tube containing Ethanoic acid
Bubbling, solid disappears
Write formulae for products of Ethanoic acid
H2, C4H6O4Mg
Identify catalyst in ethene reaction
Alumina - white powder
Why is there a risk of hot glassware shattering due to rapid cooling and how can this be minimised?
Cold water enters hot test tube
Loosen stopper before reducing heat
Why in recrystallisation is there no need to carry out a filtration of the hot solution
No insoluble impurities, sodium chloride soluble
State one advantage of suction filtration over gravity filtration
Faster
Explain how you could verify that the recrystallised benzoic acid was purer than the original sample
Measure melting points of both samples, purer melting point higher
What was observed when water was dropped onto calcium carbide
Reaction turns milky, bubbling
State and explain 2 safety precautions when preparing ethene and ethyne
Keep long hair tied back - avoids burns
Wear mask - avoid contact with chemicals
Why were the first few test tubes of preparation of ethyne discarded
Contain air
Compare observations in ethyne and ethene tests
Ethyne flame smokier than ethenes, ethene flame cleaner than ethynes
Write a balanced equation for the complete combustion of ethyne in oxygen
C2H2 + 02 ->CO2 + H2O
Needs to be balanced
Name a reagent used to test gases for unsaturation
Bromine solution
How would you test ethyne and ethene for unsaturation
Bromine solution decolourises if unsaturated
Describe a test to confirm that ethanal can be very easily oxidised
1) Add fehlings
2) heat gently
3) giving brick red precipitate
If water was added to liquid x and y and shaken and white was observed in x and y was colourless. Identify x and y
X = Eugenol Y = Ethanoic acid
A small volume of cyclohexane was added to eugenol and shaken. What was observed when it was left to stand
Two layers
Write a balanced equation for magnesium and Ethanoic acid
2CH3COOH + Mg -> (CH3COO)2Mg + H2
Name a laboratory technique to purify impure benzoic acid
Recrystallisation
