How Much Water Must Be Supplied to Saturate Breathed Air and Its Caloric Impact?

In summary, the problem involves determining the amount of water per day that the internal membranes must supply to saturate the air at 98.6 degrees F, assuming all moisture is exhaled. This can be calculated by finding the difference in water vapor pressure at 68 degrees F and 98.6 degrees F. The calorie portion of the problem can be solved using a formula, but the relative humidity must be taken into consideration. The relative humidity at 68 degrees F is 50% which is equivalent to 8.65 g/m^3, while at 98.6 degrees F it is 100% which is equivalent to 44 g/m^3. The question requires determining the additional amount of water that the membranes must
  • #1
jason.frost
6
0

Homework Statement


If a person breathes 10 liters per minute of air at 68 degrees F and 50% relative humidity, how much water per day must the internal membranes supply to saturate the air at 98.6 degrees F? (Assume all the moisture is exhaled). I f each gram of water extracts 580 calories as it is vaporized, how much daily heat loss in kilocalories (food calories) does this represent?


Homework Equations





The Attempt at a Solution


My instructor provided us that saturation vapor pressure at 20 degrees C is 17.3 g/m cubed and at 37 degrees C is 44.0 g/m cubed.

I believe I should be able to figure out the calorie portion of the problem by using a formula from my book but I am unsure about the relative humidity part. Unless I am just over looking the information that is there.

Would I need to find the number of g/m^3 for the 10 liters to start? I'm just not quite sure.

Thanks in advance for any help.
 
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  • #2
Assuming that 50% relative humidity is half the amount of water as 100% relative humidity ( I don't remember the defns).
You know the mass of water in the 10L breathed in (68deg = 20c)
You know the mass of water in the 10L breathed out
Work out the mass of extra water that comes from the person
Work out how much energy it takes to evaporate this much water.

Be careful about working in different units.
 
  • #3
So would the relative humidity at 68F/20C be 8.65g/m^3, being that it's 50%?
And the relative humidity at 98.6F/37C would be 44g/m^3 since it is 100%?

Does the question want to how much MORE water the membranes would have to produce to completely saturate the air at 37 degrees C?
 
  • #4
Yes, that's my reading of it
 
  • #5
hey

i have no idea how to do or set up this problem can you help me in any way?...
 

FAQ: How Much Water Must Be Supplied to Saturate Breathed Air and Its Caloric Impact?

1. What is heat?

Heat is a form of energy that is transferred from one object to another due to a difference in temperature. It is typically measured in units of joules (J) or calories (cal).

2. How is heat related to temperature?

Temperature is a measure of the average kinetic energy of the particles in a substance. Heat is the total energy of the particles in a substance, including both their kinetic and potential energy. As temperature increases, so does the amount of heat in a substance.

3. What is relative humidity?

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

4. How does relative humidity affect our perception of heat?

Higher relative humidity can make the air feel warmer because our bodies rely on evaporation to cool down. When the air is already saturated with water vapor, our sweat evaporates less efficiently, making us feel hotter.

5. How is heat and relative humidity related to the formation of clouds?

As air rises, it expands and cools. As it cools, its ability to hold water vapor decreases, leading to condensation and the formation of clouds. The amount of heat and relative humidity in the air can influence the type and height of clouds that form.

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