How in the bomb calorimeter the water is recondensed?

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Homework Help Overview

The discussion revolves around the functioning of a bomb calorimeter, specifically focusing on the recondensation of steam within the device. Participants are exploring the principles behind the calorimeter's operation, including the implications of constant volume and the effects of pressure on the condensation process.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning how steam is recondensed in the bomb calorimeter despite the limited amount of water present. They are also discussing the meaning of constant volume in this context and its implications for pressure and boiling point.

Discussion Status

The discussion is active, with participants seeking clarification on the mechanisms at play in the bomb calorimeter. Some have provided insights about the relationship between pressure and boiling point, while others are probing deeper into the rationale behind using a constant volume setup.

Contextual Notes

There are references to specific design features of bomb calorimeters, such as the introduction of pure oxygen and the fixed volume of the chamber, which are under discussion but not fully resolved. Participants are also considering the implications of high pressure and humidity on the condensation of steam.

Elz
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1. In the bomb calorimeter used for the test the water is recondensed after it is vaporized

In the bomb calorimeter we measure the HHV as the steam formed there is condensed. What I want to know is how the steam is re condensed? In the wikipedia it says In more recent calorimeter designs, the whole bomb, pressurized with excess pure oxygen (typically at 30atm) and containing a weighed mass of a sample (typically 1-1.5 g) and a small fixed amount of water (to saturate the internal atmosphere, thus ensuring that all water produced is liquid, and removing the need to include enthalpy of vaporization in calculations), is submerged under a known volume of water
...
http://en.wikipedia.org/wiki/Calorimeter#Bomb_calorimeters

If a small amount of water is admitted into the bomb then how it is condensing the steam? Also Bomb calorimeter is called a constant volume calorimeter, What does this constant volume mean? As the bomb calorimeter has to withstand high pressure so what does this constant volume refer to?

Please help me with this.
 
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Any additional steam would increase the humidity above 100%, therefore it condenses (unless the temperature increases significantly).
What does this constant volume mean?
What is unclear about constant volume? The whole setup has a fixed volume, it cannot expand or emit any stuff.
As the bomb calorimeter has to withstand high pressure
That is a side-effect of the constant volume: The pressure can be high.
 
mfb said:
Any additional steam would increase the humidity above 100%, therefore it condenses (unless the temperature increases significantly).

Additional steam?
I also found in a report that introducing pure oxygen to the bomb would increase the pressure in an isochoric chamber, thus ensuring that the water would be liquid. Can you please explain how it works? I mean i just want to be clear about the mechanism.

What is unclear about constant volume?

Why it is done in constant volume?

Thanks for you response.
 
I also found in a report that introducing pure oxygen to the bomb would increase the pressure in an isochoric chamber, thus ensuring that the water would be liquid. Can you please explain how it works? I mean i just want to be clear about the mechanism.
A high pressure increases the boiling point.
Why it is done in constant volume?
The scientist wanted to study something at constant volume, I think. Why? That depends on the experiment.
 
Well, it is a bomb calorimeter.

If the reaction didn't occur at constant volume, that would imply that the bomb spread itself all over the lab.
 

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