How Do You Calculate the Vapor Pressure of Water at Different Temperatures?

It should be divided by R, not multiplied. So it should be -(43900/8.31) * [(1/332.8) - (1/298)]. And then take the natural log of both sides to solve for P2. In summary, the vapor pressure (atm) of water at 59.8°C can be calculated using the Clausius-Clapeyron equation by first converting the given temperature and vapor pressure values to Kelvin and atm units, respectively. By plugging these values into the equation and taking the natural log of both sides, the unknown vapor pressure (P2) can be solved for. The incorrect result may be due to a typo in the heat of vaporization value, which should be
  • #1
deteam
24
0

Homework Statement


The vapor pressure of water at 25.0 C is 23.8 torr, and the heat of vaporization is 43.9 kJ/mol. What is the vapor pressure (atm) of water at 59.8C?

Homework Equations


Clausius-Clapeyron equation.
ln(P2/P1)=(ΔH/R)((1/T1)-(1/T2))

The Attempt at a Solution



P2=?
P1=23.8 torr = .031315789 atm
ΔH=43.9 KJ/mol=43900 J/mol
R= 8.31 (J)/(mol∙K)
T1=25.0°C=298 K
T2=59.8°C=332.8 K

plugged into the equation and keep getting the wrong answer.

Can someone please help.

ln(p2) - ln(.031315789) = -(439005)/(8.31) * [(1/332.8) - (1/298)]

HELP idk what i did wrong
 
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  • #2
Atm is not KMS units
 
  • #3
flatmaster said:
Atm is not KMS units
That shouldn't matter as long as P1 and P2 have the same units.

The setup looks good, but it does look like the calculations have a typo in the heat of vaporization though.
 
Last edited:

What is vapor pressure?

Vapor pressure is the pressure exerted by the gaseous form of a substance in equilibrium with its liquid or solid form. In the case of water, it is the pressure exerted by water vapor in equilibrium with liquid water at a given temperature.

How is vapor pressure of water affected by temperature?

The vapor pressure of water increases with increasing temperature. This is because as the temperature increases, more water molecules have enough energy to escape from the liquid phase and enter the gas phase, resulting in a higher vapor pressure.

What is the relationship between vapor pressure and humidity?

Vapor pressure is directly related to humidity. When the vapor pressure of water is equal to the maximum vapor pressure that the air can hold at a given temperature, the air is said to be saturated and the humidity is 100%. As the vapor pressure increases, so does the humidity.

How is vapor pressure of water measured?

Vapor pressure of water is typically measured using a device called a hygrometer. This device measures the amount of water vapor in the air and calculates the vapor pressure based on the temperature and humidity.

What factors can affect the vapor pressure of water?

The vapor pressure of water can be affected by factors such as temperature, humidity, air pressure, and the presence of other substances. Changes in these factors can cause the vapor pressure of water to increase or decrease.

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