Relationship of vapour pressure and Dew Point

In summary: C with a dew point of 26 degrees C and a total atmospheric pressure of 100.7kPa. Using the equations for molal humidity and relative humidity, he calculated a value of 3.45% for the molal humidity. As there are no given answers for this question, the accuracy of this result cannot be confirmed. In summary, Chetan has found the molal humidity and relative humidity of moist air at 32 degrees C with a dew point of 26 degrees C and a total atmospheric pressure of 100.7kPa. Using the equations for molal humidity and relative humidity, he calculated a value of 3
  • #1
miniradman
196
0

Homework Statement


Moist air at 32 degrees C has a dew point of 26 degrees C. The total or atmospheric pressure
is 100.7kPa.

find the:
Molal Humidity
Relative Humidity

Homework Equations


Molal Humidity = [itex]\frac{P_{i}}{P_{tot} - P_{i}}[/itex]
Relative Humidity = [itex]\frac{P_{i}}{P_{vap}}[/itex]


The Attempt at a Solution


I'm thinking I can simply sub in the vapour pressure for the dew point (looking at a pressure table) straight in as the partial pressure for molal humidity.

I got an answer of 3.45%, using equation for molal humidity. I have no answers for this particular question, so I'm not sure if this is correct.
 
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  • #2
miniradman said:

Homework Statement


Moist air at 32 degrees C has a dew point of 26 degrees C. The total or atmospheric pressure
is 100.7kPa.

find the:
Molal Humidity
Relative Humidity

Homework Equations


Molal Humidity = [itex]\frac{P_{i}}{P_{tot} - P_{i}}[/itex]
Relative Humidity = [itex]\frac{P_{i}}{P_{vap}}[/itex]


The Attempt at a Solution


I'm thinking I can simply sub in the vapour pressure for the dew point (looking at a pressure table) straight in as the partial pressure for molal humidity.

I got an answer of 3.45%, using equation for molal humidity. I have no answers for this particular question, so I'm not sure if this is correct.
Looks correct.

Chet
 

FAQ: Relationship of vapour pressure and Dew Point

What is vapour pressure?

Vapour pressure is the pressure exerted by the gas phase of a substance when it is in equilibrium with its liquid or solid phase.

What is dew point?

Dew point is the temperature at which the air becomes saturated with water vapour, causing condensation to occur.

How are vapour pressure and dew point related?

Vapour pressure and dew point are related because as the temperature increases, the amount of water vapour the air can hold also increases, resulting in a higher vapour pressure and a higher dew point.

How does humidity affect the relationship between vapour pressure and dew point?

Humidity is an important factor in the relationship between vapour pressure and dew point. Higher humidity levels mean there is more water vapour in the air, resulting in a higher vapour pressure and a higher dew point.

Why is understanding the relationship between vapour pressure and dew point important?

Understanding the relationship between vapour pressure and dew point is important in meteorology, as it helps predict weather conditions and patterns. It is also important in various industrial processes, such as in food and pharmaceutical industries, where controlling humidity levels is crucial in maintaining product quality and safety.

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