Robert asks…
what is the boiling point of diethyl ether using enthalpy of vapourisation and entropy?
diethyl ether ( C4 H10 O) has an ΔvapH of 28.36 kJ/mol and the phase change from liquid to gas has an ΔS° of 96.6 J/mol/K. what is the normal boiling point of diethyl ether?
weight loss cardiff answers:
At the normal boiling point, the liquid and gas phases of a material are in equilibrium. That means the free energy change for the reaction:
liquid -> gas
is zero.
You should also know that ΔG = ΔH – T*ΔS, so at equilibrium:
T = ΔH/ΔS
In this case, you are given the enthalpy and entropy of vaporization, so:
T_boiling = (28,360 J/mol)/(96.6 J/(mol*K)) = 294 K
John asks…
why is it better to use diethyl ether when performing trimyristin extraction from numeg instead of acetone or?
why is it better to use diethyl ether when performing trimyristin extraction from numeg instead of acetone or ethanol? does it have to do with the solubilities of trim. in each of these solvents? how would you rank trimyristin’s solubility in each of these solvents?
weight loss cardiff answers:
Hmm, i wonder why you’d want to do that?
Seriously though, i’d say it was to do with flammability and possibly toxicity, but that’s just a guess.
George asks…
When you add salicylic acid-naphthalene mixture in a diethyl ether with a saturated aqueous sodium bicarbonate?
When you add salicylic acid-naphthalene mixture in a diethyl ether with a saturated aqueous sodium bicarbonate solution, what kind of gas do they form?
weight loss cardiff answers:
CO2(g) is evolved…
Here’s the balanced equation.
C6H4(OH)-COOH (salicylic acid) + NaHCO3 (sodium bicarbonate) –> C6H4(OH)-COO-Na+ (sodium salicylate) + CO2 (carbon dioxide) + H2O
A wash with aqueous sodium barcarbonate solution is usually done to remove any unreacted acidic reagent (salicylic acid, in this case) from the reaction mixture. As you can see, salicylic acid reacts with sodium bicarb to form sodium salicylate, which is water soluble are therefore goes into the water layer. Meanwhile, the organic layer now only contains naphthalene, which can be recovered by evaporation of the diethyl ether solvent.
Hope this helps!!!
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