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

In summary, the question is asking if tea can be made at a certain pressure, specifically at an altitude of 4km. If the temperature at this altitude is greater than 97 degrees celsius, then the tea will be considered "good". To solve this, the Clausius-clapeyron equation can be used, along with some algebra and substitution of values. Tables are not necessary for this solution.
  • #1
H.fulls
19
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*[itex]10^{4}[/itex]Pa) . Given that latent heat of vaporisation for water is 2.4*[itex]10^{6}[/itex] J/kg and water has a molar mass of 18g.

Homework Equations


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

Ideal gas equation pV=nRT

The Attempt at a Solution



Tried to integrate so have [itex]\int\frac{1}{p}dp[/itex]=[itex]\frac{L}{R}[/itex][itex]\int\frac{1}{T^{2}}dT[/itex]
from substituting in V = [itex]\frac{RT}{p}[/itex] 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
  • #2


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?
 
  • #3


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


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.
 
  • #5


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 :/
 

1. How does pressure affect the boiling point of water?

The boiling point of water increases as pressure increases. This is because the increased pressure compresses the molecules of water, making it harder for them to escape into the gas phase. This requires a higher temperature to reach the boiling point.

2. Can you make tea at higher altitudes where the air pressure is lower?

Yes, it is possible to make tea at higher altitudes where the air pressure is lower. However, the lower air pressure will cause water to boil at a lower temperature, so it may take longer for the water to reach the desired temperature for brewing tea.

3. How does the temperature of the water affect the quality of the tea?

The temperature of the water can greatly affect the quality of the tea. For example, if the water is too hot, it can scald the tea leaves and result in a bitter taste. On the other hand, if the water is not hot enough, the tea may not fully extract its flavors and may taste weak.

4. Is it better to boil water for tea in a pot or in the microwave?

Both methods can be used to boil water for tea, but using a pot is generally recommended. This is because the heat is more evenly distributed and the water can reach a consistent temperature throughout. In contrast, microwaves can create hot spots in the water, resulting in uneven heating.

5. Can you use a pressure cooker to make tea?

No, it is not recommended to use a pressure cooker to make tea. The high pressure in a pressure cooker can cause the water to boil at a much higher temperature, resulting in tea that is over-extracted and bitter. It is best to use a pot or kettle to make tea at a consistent temperature.

Similar threads

  • Advanced Physics Homework Help
Replies
5
Views
943
  • Introductory Physics Homework Help
Replies
14
Views
3K
  • Introductory Physics Homework Help
Replies
3
Views
984
  • Advanced Physics Homework Help
Replies
4
Views
1K
  • Advanced Physics Homework Help
Replies
2
Views
2K
  • Biology and Chemistry Homework Help
Replies
2
Views
3K
  • Advanced Physics Homework Help
Replies
1
Views
2K
  • Materials and Chemical Engineering
Replies
6
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Advanced Physics Homework Help
Replies
5
Views
3K
Back
Top