Rinse out the test tube and fill it to the top with tap water. Cover the test tube with the aluminum foil. Measure and record the mass of the test tube, water, and foil. 3 data table trial 1 Trial 2 Mass of test tube and foil cover (g) Temperature of hot water bath (C) Mass of test tube and foil and gas sample (g) Barometric pressure (atm) Mass of test tube and foil and water (g) pre-lab questions. What is the difference between a vapor and a gas? A student performs an experiment designed to determine the molar mass of a sample of an unknown volatile liquid. The following data was collected: Trial 1 Mass of test tube and foil cover (g) g Temperature of water bath (C) 99 c mass of test tube and foil and condensed gas (g) g Barometric pressure (atm) atm Mass of test tube and foil and. (b) Assuming the density of water to.00 g/ml, determine the total volume of the test tube.
Chm142L, lab, report 3 distillation evaporation
Immerse the postal temperature Probe in story the hot-water bath (see figure 1). Do not allow the tip of the probe to touch the beaker. Heat the hot-water bath to boiling and maintain the boiling as your sample of liquid vaporizes. Note that some of your sample will escape the test tube through the needle hole in the foil. This process also serves to flush the air out of the test tube. Keep the test tube in the boiling-water bath for at least three minutes after all of the liquid in the test tube has vaporized. Watch the temperature readings and record the temperature of the boiling water bath, which will be used in the ideal gas law calculations. Use a test-tube holder to quickly transfer the test tube to the ice water bath. Cool the test tube for about one minute, then remove it and dry it completely. Measure and record the mass of the test tube and the aluminum foil top. Record the room s barometric pressure.
Start proposal the data collection program. Be sure the program shows the correct readings for the probe. There is no need to store and graph the data for this experiment. Obtain a liquid sample of an unknown volatile compound. Pour about.5 ml of the liquid into the test tube and quickly cover the test tube with the aluminum foil. Use your fingernail to make an air-tight seal with the foil just under the lip of the test tube. Place the test tube in the hot water bath. Make sure that the foil is above the water level, but submerge your test tube as far as possible without making contact with the bottom of the beaker (see figure 1).
Trim a piece of aluminum foil so that it just covers the top of a small, mm, test tube. Use a needle to make a small roles hole in the center of the foil. Measure and record the mass of the test tube and foil. Prepare a hot-water bath by warming about 300 ml of tap water in a 400 ml beaker. Keep the beaker on a hot plate once the water is warm. You want database it to boil by Step Use a second 400 ml beaker to prepare an ice-water bath. Set up the data collection system. Connect a temperature Probe to the interface.
Determine the molar mass of an unknown liquid. Best results are obtained when the test tube containing the sample is submerged in the water bath to just below the foil cap. Consider using tall form beakers for your water baths. Figure 1 materials data collection Mechanism Temperature Probe gas Pressure sensor or barometer ring stand two utility clamps aluminum foil ice unknown volatile liquid fume hood test tube, mm, and holder two 400 ml beakers (or larger) hot plate analytical balance needle tissues or paper. A conventional barometer or a gas Pressure sensor may be used. Obtain and wear goggles. Conduct this experiment in a fume hood or well-ventilated area.
Properties of water - wikipedia
Assume that urea is event non-volatile. The vapor pressure of pure water.77 mmHg at 25 c solution: Psoln (Psolvent) (mole fraction of solvent).83 (23.77) (x).960 (this is the mole fraction of water) mole fraction of urea.040 Let us assume a total.000 mole. Change.960 mole to grams of water:.960mol times.015.2944 g Calculate molality:.040 mol /.0172944.31 m Return to discusson of nonvolatile effect on vapor pressure go to Problems 11-25 (incomplete) Return to solutions Menu. 1 Determination of Molar Mass by vapor Density One of the properties that helps characterize a substance is its molar mass. If the substance in question is a volatile liquid, a common method to determine its molar mass is to vaporize it and apply the ideal gas law, pv nrt to the data collected. Because the liquid is volatile, it can easily be converted to a vapor.
Volatile substances are usually composed of nonpolar molecules. As a result the molecules have primarily london dispersion forces and very little thermal energy is required to overcome these attractive forces since the molecules are relatively small. Therefore, the liquid vaporizes easily and quickly at temperatures less than 100. While the substance is in the vapor phase, you can measure its volume, pressure, and temperature. You can then use the ideal gas law to calculate the number of moles of the substance. Finally, you can use the number of moles of the gas to calculate molar mass. Objectives in this experiment, you will evaporate a sample of a liquid substance and measure certain physical properties of the substance as it condenses.
When.00 g of an unknown non-volatile substance is dissolved in 100.0 g of benzene, the vapor pressure of the solution.0 c.1199 atm. Calculate the mole fraction of solute in the solution, assuming no dissociation by the solute. Solution: 1) Because solute is non-volatile, the vapor of the solution contains only benzene. All of the unknown substance remains in solution. Assuming an ideal mixture, the vapor pressure of the solution is given by raoult's Law: Psolution (Psolvent) (χsolvent) 2) The mole fraction of benzene in this mixture is: Psolution (Pbenzene) (χbenzene) χbenzene psolution / Pbenzene.1199 atm /.1252 atm.9576677 3) The mole fractions. So, for this solution: χbenzene χsolute 1 Hence: χsolute 1 - χbenzene 1 -.04233 (to four sig figs) Problem 8: What is the vapor pressure.0 c of a solution composed.71 g of naphthalene (a non-volatile compound, mw 128 g/mol) and.
(The vapor pressure of pure ethanol.0 c is 96 torr. ) Solution: 1) The vapor pressure of this kind of solvent is related to the mole fraction of the solvent and its pure vapor pressure: vapor pressure of the solution mole fraction of solvent times vapor pressure of the pure solvent This is known. 2) Calculating: moles naphthalene -.71 g / 128 g/mol.334 mol moles ethanol -.65 g /.02 g/mol.883 mol mole fraction ethanol -.883 / (0.883.334).726 vapor pressure of solution - 96 torr times.726. Torr Problem 9: A nonvolatile organic compound Z was used to make up a solution. Solution A contains.00 g of Z dissolved in 100. G of water and has a vapor pressure of 754.5 mmHg at the normal boiling point of water. Solution: 1) Use raoult's Law to determine mole fraction of the solvent: Psolution (χsolvent) (Psolvent) 754.5 torr (χsolvent) (760.0 torr) Note: 760.0 torr is the vapor pressure of water at its normal boiling point, 100 c χsolvent 754.5 torr / 760.0 torr χsolvent. ) Use the mole fraction and the moles of water to determine the moles of Z: 100. G /.015 g/mol.55093 mol.55093 / (5.55093 x).040464 mol 3) Calculate molar mass of Z:.00 g /.040464 mol 124 g/mol (to three sig figs) Problem 10: What is the molality of an aqueous solution of urea, co(NH2)2, if the.
Lab, quality (ish) Distillation Apparatus
The vapor pressure of the resulting solution.6 torr. Calculate the molar mass. Solution: 1) Use raoult's Law to determine mole fraction of the solvent: Psolution (χsolvent) (Psolvent).6 torr (χsolvent) (31.1 torr) χsolvent.6 torr /.1 torr χsolvent. ) Use the mole fraction and the moles of water to determine the moles of Y: 350. G /.015 g/mol.428254 mol.428254 / (19.428254 x) (0.91961415) (19.428254 x).428254.8665.91961415x.428254.91961415x.561754.69827 mol 3) Calculate molar mass of Y:.8 g /.69827 mol.1 g/mol (to three sig figs) Problem thesis 5: The vapor pressure. What is the vapor pressure.50 molal C6H12O6 Solution: 1) covert the molality to a mole fraction. First, calculate total moles:.50 m C6H12O6.50 mol /.00 kg H2O 1000 g /.015 g/mol.51 mol.51 mol.50 mol.01 mol 2) we need the mole fraction of water:.51 /.01.9569 3) Use raoult's law: Psolution (χsolvent) (Psolvent). (Benzene c6H6.12 g/mol. The vapor pressure of benzene.03 mm Hg.0.) Solution: Use raoult's law: Psolution (Psolvent) (χsolvent).41 (73.03) (2.66 / (2.66x).41 194.2598 / (2.66x).41 194.2598 / (2.66x) 194.2598 189.9506.41x.41x.3092.0603445 mol 288.4 g/mol times.0603445 mol.
The vapor pressure of water at this temperature.362 torr. Solution: we will assume that B does not ionize in solution. 1) Determine mole fraction of solvent that produces a english solution vapor pressure.756 torr: Psolution (χsolvent) (Psolvent).756 torr (x) (42.362 torr).5608 2) Determine moles of compound B needed to produce the above solvent mole fraction:.5608.88 / (13.88 B).7839. Comment: this is a completely ridiculous amount to dissolve in 250.0 g of water, but that's not the point. The point is to solve the problem. Problem 4:.6 c, pure water has a vapor pressure.1 torr. A solution is prepared by adding.8 g of "y a nonvolatile non-electrolyte to 350.
(χsolvent) (Psolvent) x (0.900) (25.756).18 mmHg (to four sig figs). Problem 2: The vapor pressure of an aqueous solution is found to.90 mmHg at. What is the mole fraction of solute in this solution? The vapor pressure of water.756 mm Hg at. Solution: Use raoult's Law: Psolution (χsolvent) (Psolvent).90 (x) (25.756).966765 (this is the solvent mole fraction) χsolute 1 -.966765.033235 χsolute.03324 (to four sig figs). Problem 3: How many grams of nonvolatile compound B (molar mass.80 g/mol) would need to be added to 250.0 g of water to produce a solution with a vapor pressure.756 torr?
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US5499531a - system and method for determining volatile
The saturation water vapor pressure is one of the most commonly needed and calculated property in meteorology and for atmospheric science. Several authors have published equations for the calculation of the water vapor pressure, separated for vapor pressure above ice and above liquid. Ddbst provides three models for both calculations as free online service: and and, water Vapor Pressure data in the dortmund Data bank. The pure component properties part (. Pcp ) of the dortmund Data bank (. Ddb ) contains experimental vapor pressure data sets, sublimation pressures, saturation vapor pressures, and vapor pressures above supercooled water. Besides these equilibrium book data the ddb also offers a lot of pvt data of water including a lot of data at supercritical conditions. Besides these experimental data, ddb contains parameters for different vapor pressure equations like antoine, wagner, dippr 101, cox, etc. Disclaimer, this calculation service is provided "as is".