Thermal physics- Can you make good tea at a certain pressure?

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Homework Help Overview

The discussion revolves around the thermal physics of brewing tea at high altitudes, specifically at an elevation of 4 km where the atmospheric pressure is significantly lower than at sea level. The original poster questions whether it is possible to brew good tea, defined as tea made at temperatures above 97 degrees Celsius, under these conditions. The problem involves the Clausius-Clapeyron equation and the properties of water, including its latent heat of vaporization.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the relationship between boiling temperature and altitude, questioning how to determine the boiling point of water at the given pressure. There are suggestions to integrate the Clausius-Clapeyron equation and to consider reference pressures and temperatures. Some participants also mention the need for tables of saturated vapor pressure.

Discussion Status

The discussion is active, with various approaches being explored. Some participants emphasize the necessity of using the Clausius-Clapeyron equation, while others suggest practical methods for determining boiling points. There is no explicit consensus on the best approach, but multiple lines of reasoning are being considered.

Contextual Notes

The problem is constrained by the requirement to use the Clausius-Clapeyron equation and the specific conditions at an altitude of 4 km. The original poster expresses uncertainty about the integration process and the limits to apply, indicating a need for further clarification on these aspects.

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Thermal physics- Can you make good tea at a certain pressure!?

Homework Statement


According to experts good tea can only be made at temperatures greater than 97 degrees celsius. If this is true, can you brew good tea at elevation 4km (Pressure = 6.2*10^{4}Pa) . Given that latent heat of vaporisation for water is 2.4*10^{6} J/kg and water has a molar mass of 18g.

Homework Equations


Clausius-clapeyron equation \frac{dp}{dT} = \frac{L}{T(V2-V1)}
but V1 is negligable so \frac{dp}{dT} = \frac{L}{TV2}

Ideal gas equation pV=nRT

The Attempt at a Solution



Tried to integrate so have \int\frac{1}{p}dp=\frac{L}{R}\int\frac{1}{T^{2}}dT
from substituting in V = \frac{RT}{p} from ideal gas equation.
But don't really know what to do from here! I don't know what limits to put in for the integral or if I am just going about this all wrong from the start!
Ive been told the clausius-clapeyron statement must be used by my professor!
Any suggestions would be helpful! Thankyou!
 
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I think what the question is really asking is, at what temperature does water boil at an altitude of 4km? If it boils at over 97C then the tea you make will be 'good', if not, it will be 'bad'.

Why don't you try integrating from p0 to p1 and from T0 to T1 where p0 and T0 are reference pressure and temperatures which you know. The question then becomes, what is the pressure at 4km above sea level?
 


JesseC said:
The question then becomes, what is the pressure at 4km above sea level?
The pressure at 4km was given.
 


Boiling is when saturated vapor pressure = atmospheric pressure. So get a table of sat. vapor pressure vs. temperature for water and see if T corresponding to your altitude pressure is > 97C.
 


rude man said:
Boiling is when saturated vapor pressure = atmospheric pressure. So get a table of sat. vapor pressure vs. temperature for water and see if T corresponding to your altitude pressure is > 97C.

The question specifically requires use of the Clausius-clapeyron equation. The answer can be reached using the equation, a couple of lines of algebra and substitution of the correct values. Tables really aren't needed :/
 

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