3) Objectives, Materials and Apparatus, Chemicals
This experiment is about steam distillation by using Dalton’s Law.
The objectives of this experiment are to demonstrate a separation of a mixture by using steam distillation and next to prove that Dalton’ Law and ideal gas law are applicable in steam distillation.
While Ideal Gas Law;
This experiment is conducted by placing 2mL of Turpentine and 15mL of water into the flask.10mL graduated cylinder is used as the receiver.All the connections are make sure tighten.Next,two boiling chips are added to ensure smooth bubbling and prevent bumping of the liquid up into the distillation head.The heating mantle is adjusted to give vigorous boiling.The first 1.5mL of distillate is discarded and the next 5mL is collected.The volumes of the water and turpentine layers in this distillate are recorded.The recorded volume is then compared with the ideal steam distillation law using the tabulated vapour pressure and densities.
The volume of water and turpentine recorded are:
In conclusion,it is proven that turpentine and water can be separated using the steam distillation.
Dalton's Law of Partial Pressures states that for a mixture of gases in a container, the total pressure is equal to the sum of the pressures of each gas. Where P1 is the partial pressure of gas 1, P2 is the partial pressure of gas 2, and so on...
In the experiment of the steam distillation,we applied the Dalton’s Law of Partiaal Pressure combined with Ideal Gas Law. Steam distillation is a special type of distillation (a separation process) for temperature sensitive materials like natural aromatic compounds. Steam distillation is employed in the manufacture of essential oil, for instance, perfumes. In this method steam is passed through the plant material containing the desired oils. It is also employed in the synthetic procedures of complex organic compounds. Eucalyptus oil and orange oil are obtained by this method in industrial scale.
Figure 1 : Laboratory set-up for steam distillation
Distillation Temperature and Composition of Distillate
As with ordinary distillations, the boiling point is the temperature at which the total vapor pressure equals the atmospheric pressure. If the vapor pressures of the two components are known at several temperatures, the distillation temperature is found readily by plotting the vapor pressure curves of the individual components and making a third curve showing the sum of the vapor pressures at the various temperature. The steam distillation temperatures will be the point where the sum equals the atmospheric pressure.
Knowing the distillation temperature of the mixture and the vapor pressures of the pure components at that temperature, one can calculate the composition of the distillate by means of Dalton’s law of partial pressures.
According to Dalton’s law, the total pressure(P) in any mixture of gases is equal to sum of the partial pressures of the individual gaseous components (ρA , ρB, etc). The proportion by volume of the two components in the distilling vapor will consequently be equal to the ratio of the partial pressures at that temperature; the molar proportion of the two components (ηA and ηB) in steam distillation will be given by the relationship ηA/ηB = ρA/ ρB, where ρA + ρB equals the atmospheric pressure. The weight proportion of the components is obtained by introducing the molecular weight (MA and MB)
Weight of A / weight of B = (ρA x MA) / (ρB x MB)
Consider a specific case, such as the steam...
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