Simple Distillation Prelab
Which of the following statements are true concerning azeotropes?
A mixture of three compounds can form an azeotrope. Azeotropes cannot be separated by simple distillation. The following statements are true concerning azeotropes: Azeotropes can occur between substances that have similar properties (ethanol and water) and also substances that have different properties (toluene and water). Azeotropes not only form between two liquids, but can also form between mixtures of three and four compounds. Azeotropes cannot be separated by simple distillation because the vapor has the same proportions as the unboiled mixture. As a result, an unknown liquid that boils at a constant temperature is not necessarily pure and can potentially be classified as an azeotrope.
A mixture of hexane and octane were separated by a simple distillation and then tested for purity using gas chromatography.Drag and drop the chemical wastes generated in this reaction into the appropriate container.
Solid waste - used kimwipe hexane, heptane, octane waste - hexane, octane glass waste - pasteur pipet Acetone - acetone
Which of the following statements about the collection of a GC trace is true? Select all that apply.
The amount of sample detected is proportional to the peak area. The stationary phase is a very high-boiling liquid adsorbed onto fire brick.
The following statements are true and correct concerning theoretical plates:
The following statements are true and correct concerning theoretical plates: The rate of heating affects the number of theoretical plates in the column. Each vaporization-condensation is called a theoretical plate. The larger the boiling point difference, the easier it is to separate two liquids and fewer theoretical plates are required. Increasing the length of the column and packing the column with glass beads or rings are methods that produce more theoretical plates. Rapid heating can drive heated vapor up the column, preventing the formation of an equilibrium that allows the lower boiling component to separate. As a result, this will decrease the number of theoretical plates and decrease the separation.
What error is introduced if the bulb of the thermometer, or the thermocouple, is too high in the distillation apparatus?
The recorded boiling point will be lower than actual because the bulb is not exposed to the hot vapor. If the bulb of the thermometer or tip of the thermocouple is placed too high in the condenser, then the hot vapors are likely to condense before they reach the thermometer. This will result in the recorded temperature being lower than the actual boiling temperature of the vapor. In order to find the boiling point that is more accurate, the bulb of the thermometer has to be positioned in a way that all the bulb will be completely exposed to the hot vapor before passing into the condenser.
A mixture of two miscible volatile liquids is distilled. Which of the following statements are true concerning the boiling point of the distillate?
The temperature range should start being recorded from when the liquid first starts to boil. If the range is within 2 °C, then the distillate can be considered pure. The temperature range should be recorded until right before the dramatic drop in temperature. The following are true statements regarding the boiling point of the distillate: The temperature range should start being recorded from when the liquid first starts to boil. The temperature range should be recorded until right before the dramatic drop in temperature. The distillate can be considered pure if the range is within 2 ° C.
Which of the following statements describe why moisture must be excluded from any sample injected into the G.C. Select all answers that apply.
Water contains dissolved salts that can clog the injector. Water signals are very broad and make interpretation of other peaks difficult.
