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

AI Thread Summary
Good tea requires brewing temperatures above 97 degrees Celsius, but at an elevation of 4 km, the atmospheric pressure is significantly lower, affecting boiling point. The Clausius-Clapeyron equation is essential for determining the boiling temperature of water at this altitude. Users suggest integrating the equation and using known reference pressures and temperatures to find the boiling point. It is crucial to compare the calculated boiling temperature with 97 degrees Celsius to assess tea quality. Ultimately, the discussion emphasizes the importance of using the correct thermodynamic principles to solve the problem.
H.fulls
Messages
19
Reaction score
0
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!
 
Physics news on Phys.org


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 :/
 
Thread 'Help with Time-Independent Perturbation Theory "Good" States Proof'
(Disclaimer: this is not a HW question. I am self-studying, and this felt like the type of question I've seen in this forum. If there is somewhere better for me to share this doubt, please let me know and I'll transfer it right away.) I am currently reviewing Chapter 7 of Introduction to QM by Griffiths. I have been stuck for an hour or so trying to understand the last paragraph of this proof (pls check the attached file). It claims that we can express Ψ_{γ}(0) as a linear combination of...
Back
Top