Test on Distillation and separation of mixtures
Distillation and Separation of Mixtures: Student Guide
Test: Distillation
20 questions
Question 1: In the fractional distillation of crude oil, the highest boiling point fractions, such as bitumen, are collected at the top of the fractionating column.
A. Yes
B. No
Explanation: Bitumen has the highest boiling points (above 400 °C) and remains as a residue at the bottom of the column. The lowest boiling point fractions, such as refinery gases, are collected at the very top.
Question 2: In the fractional distillation of crude oil, bitumen/asphalt has boiling points above 400 °C.
A. Yes
B. No
Explanation: The study materials state under the 'Distillation of Crude Oil' section that 'Bitumen/Asphalt: Highest boiling points, remains as a residue at the bottom of the column (above 400 °C)'.
Question 3: When setting up a distillation apparatus, the thermometer bulb should be placed low enough in the distillation flask to measure the temperature of the boiling liquid rather than the vapor.
A. Yes
B. No
Explanation: The thermometer's bulb must be placed to accurately measure the temperature of the vapor that is about to enter the condenser, which corresponds to the boiling point of the substance being distilled. Placing it too low would cause it to measure the temperature of the boiling liquid, which is a common error and not the correct procedure for measuring the vapor temperature.
Question 4: Fractional distillation can fully separate a mixture of ethanol and water, yielding 100% pure ethanol and 100% pure water.
A. Yes
B. No
Explanation: Fractional distillation can effectively separate ethanol from water, but only up to the azeotropic composition, which is approximately 95.6% ethanol by mass, not 100% pure components.
Question 5: During a virtual laboratory simulation for separating ethanol and water using fractional distillation, the thermometer would stabilize around 78 °C as ethanol distills.
A. Yes
B. No
Explanation: In a virtual laboratory simulation for mixtures like ethanol and water, you would first observe the thermometer stabilizing around 78 °C as ethanol distills.