2007-04-05 02:31:17 · 4 answers · asked by whzkid 1 in Science & Mathematics ➔ Chemistry
The boiling point of a mixture will be dependent on the vapour pressure of the component within the mixture and the atmospheric pressure, and the application of Raoult's law, which is the vapour pressure of the component in the mixture multiplied by the mole fraction of that component in the liquid . The summation of the partial pressures for each component must equal the atmospheric pressure for the liquid to boil. The vapour pressure are highly sensitive to temperature and normally a relationship exists between the two parameters (normally the natural log of the vapour pressure is inversely proportional to temperature)i.e
ln (p) = A - B/T, where A and B are constant which vary from substance to substance.
To demonstrate I will use a three component mixture of A, B, an C, having vapour pressure pA, pB, and pC, and mole fraction of xA, xB, and xC, boiling at temperature T and at atmospheric pressure, PT. Then
pAxA + pBxB + pCxC = PT
The calculation would involve guessing an initial value of temperature, and then solve iteratively until the sum of the partial pressure is equal to the atmospheric pressure. This is in the ideal world, but most substance deviate from Raoult's law and then activity coefficients need to be calculated and this become very time consuming and complicated. This is where software comes in and you will find software for the design of distillation columns useful.
2007-04-05 02:58:44 · answer #1 · answered by The exclamation mark 6 · 0⤊ 0⤋
Generally you take the lowest boiling point and add a few degrees, if these are not close! You see this in distillation of alcohol. just over 170 and 212 in the F scale. It could take a few distillations, but that is how it is done. Of course the mixture is fully in one mix. But some are much easier.. those that will not mix.Check out how we do those. Earl
2016-03-29 00:50:46 · answer #2 · answered by Anonymous · 0⤊ 0⤋
1) Apply heat to the mixture
2) As soon as it begins to boil, use a thermometer to measure the temperature. this temperature recorded is the boiling point.
2007-04-05 09:30:01 · answer #3 · answered by J D 3 · 0⤊ 1⤋
Put a thermometer in it and bring it to a boil.. then read the thermometer.
2007-04-05 02:35:21 · answer #4 · answered by ♥Tom♥ 6 · 0⤊ 2⤋