Relative Humidity Changes in a Closed Room

In summary, to reduce the relative humidity of air in a room with a volume of 2000 cubic meters from 80% to 50%, a mass of 6.9 kg of water vapor must be removed. However, upon further calculation, the correct mass is actually double at 13.8 kg.
  • #1
slaw155
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Homework Statement


A room with volume 2000 cubic metres has air at T=25degrees Celsius with relative humidity 80%. Density of water vapor in saturated air at 25deg Celsius is 22.8g/m^3. Temperature and pressure of room remains constant. What mass of water vapor must be removed from this air to reduce relative humidity to 50%?

Homework Equations



relative humidity/100 = water vapor pressure/saturated water pressure

The Attempt at a Solution


using above formula and density definition we get (18.3x2000)-(11.4x2000) = 6.9kg.
However the textbook answer is double this? Where have I gone wrong?
 
Last edited:
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  • #2
slaw155 said:
using density = mass/volume we get (18.3x2000)-(11.4x2000) = 6.9kg.
Try that computation again.
 

1. What is relative humidity?

Relative humidity is the measure of water vapor in the air compared to the maximum amount of water vapor the air can hold at a specific temperature and pressure. It is expressed as a percentage.

2. How does relative humidity affect the weather?

Relative humidity plays a crucial role in determining the weather conditions. High relative humidity often leads to cloudy and wet weather, while low relative humidity can result in dry and hot weather. It also affects the rate of evaporation and precipitation.

3. What causes changes in relative humidity?

The main factors that cause changes in relative humidity are temperature and the amount of water vapor in the air. As temperature increases, the air can hold more water vapor, leading to a decrease in relative humidity. Conversely, a decrease in temperature results in an increase in relative humidity.

4. How does relative humidity impact human health?

High relative humidity can make the air feel heavy and uncomfortable, causing difficulties in breathing and exacerbating respiratory conditions. Low relative humidity, on the other hand, can lead to dry skin, irritated eyes, and respiratory infections. Maintaining a relative humidity between 40-60% is considered ideal for human health.

5. Can relative humidity be controlled?

Yes, relative humidity can be controlled through the use of air conditioning and dehumidifiers. Air conditioners cool the air and remove excess moisture, while dehumidifiers specifically target and remove excess water vapor from the air. It is important to monitor and control relative humidity levels to maintain a comfortable and healthy environment.

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