Inside the distillation columns, the
A. Highest temperatures is near the feed plate
B. Driving force for the liquid flow is its weight
C. Vapors are not always at their dew points
D. All of the above
Answer: Option D
Solution (By Examveda Team)
Option D: All of the above is the correct answer.Option A: Highest temperature is near the feed plate
This is true because the feed plate is generally located between the rectifying and stripping sections. Since the bottom of the column is hotter (to vaporize the liquid) and the top is cooler (to condense vapors), the feed plate lies between these extremes and usually has a relatively high temperature, especially in comparison to the overhead.
Option B: Driving force for the liquid flow is its weight
This is correct. In a distillation column, the trays are arranged vertically, and gravity causes the liquid to flow from one tray to the next lower one through downcomers. Thus, the liquid flow is driven by its weight.
Option C: Vapors are not always at their dew points
Also true. Vapors in the column can be superheated or in equilibrium with liquid depending on the location and thermal gradients. Therefore, they are not necessarily always at their dew point.
Since all the individual statements are correct, the correct answer is: Option D: All of the above.
This Question Belongs to Chemical Engineering >> Mass Transfer
The correct answer is:
✅ D. All of the above
Let's break it down:
A. Highest temperature is near the feed plate ✅
In a distillation column, the bottom is hottest and the top is coldest.
The feed tray is typically placed where the temperature is appropriate for the feed's condition (e.g., saturated liquid or vapor).
So, the highest temperature is around or just below the feed plate, especially if the feed is hot.
This statement is generally valid depending on feed condition and placement.
B. Driving force for the liquid flow is its weight ✅
Liquid flows downward by gravity from one tray to the next.
The driving force is the hydrostatic head — i.e., the weight of the liquid.
So yes, this is correct.
C. Vapors are not always at their dew points ✅
Vapors rising up the column are often superheated slightly due to:
Non-equilibrium stages
Heat losses or gains
Tray inefficiencies
Therefore, they are not always at exact dew point temperature.
✅ Final Answer:
D. All of the above
You said:
Inside the distillation columns, the
A. Highest temperatures is near the feed plate
B. Driving force for the liquid flow is its weight
C. Vapors are not always at their dew points
D. All of the above
ChatGPT said:
The correct answer is:
✅ D. All of the above
Here's the reasoning for each option:
A. Highest temperature is near the feed plate ✅
In a distillation column, temperature decreases from bottom to top.
The feed plate is usually located where the feed can best be used — sometimes near the middle.
If the feed is a hot liquid or vapor, the feed tray and the region below it are typically hotter than trays above.
So, it's reasonable to say the highest temperatures are near (or just below) the feed plate, depending on the feed condition.
B. Driving force for the liquid flow is its weight ✅
Liquid flows downward from tray to tray due to gravity.
There is no pump between trays; the weight (hydrostatic pressure) of the liquid provides the driving force.
So this statement is correct.
C. Vapors are not always at their dew points ✅
Vapors rising in the column are often not in equilibrium with the liquid phase.
Due to tray inefficiencies, non-ideal mixing, or heat losses, vapor may be slightly superheated.
So, they are not always at their dew point temperatures.
✅ Final Answer:
D.