Closed container vs Open container for calorimetry

In summary, if the reaction Mg + HCl --> MgCl2 + H2 is performed in a closed calorimeter, the measured temperature will not increase as much as in an open calorimeter due to the compressed H2 having a greater heat capacity compared to air. The pressure of the gas will increase, but it will not have a significant effect on the temperature of the liquid below it. Additionally, H2 does have a nonzero heat capacity which will contribute to the temperature change in the calorimeter.
  • #1
Matthew Hoffman
4
0
So let's say I do the reaction Mg + HCl --> MgCl2 + H2 in an open calorimeter. I measure a certain temperature change in the calorimeter, let's say an increase of 12 degrees C. Keeping all other variables the same, if I perform this experiment in a closed calorimeter, what will happen to the measured temperature? I know the pressure of the gas will increase because of the compressed H2, but will this have any affect on the temperature of the liquid below it?
 
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  • #2
Does the H2 have a non-zero heat capacity?
 
  • #3
H2 does have a nonzero heat capacity. At 300K, it is 14.31 (kJ/(kg K)). Compared to air, which has a value of 1.00. And in a closed container, the mixture of gases would contain much more H2 than in an open container where it would escape. Am I headed in the right direction here?
 
  • #4
Matthew Hoffman said:
Am I headed in the right direction here?
... and?
 
  • #5
And... since H2 has a greater heat capacity its temperature will not increase as much as plain air, so that means the measured temperature in the calorimeter would be less?
 
  • #6
Matthew Hoffman said:
H2 does have a nonzero heat capacity.
Period, no need to compare it to air. Do you have any air reacting?
 
  • #7
No, the reaction is only taking place in the liquid
 

What is the difference between a closed container and an open container for calorimetry?

A closed container for calorimetry is a setup in which the system being studied is completely sealed and isolated from the external environment, while an open container allows for exchange of energy and matter with the surroundings.

When is it appropriate to use a closed container for calorimetry?

A closed container is typically used when studying systems that are undergoing a chemical reaction or phase transition, as it allows for accurate measurement of the heat exchanged during these processes without any interference from the surrounding environment.

What are the advantages of using an open container for calorimetry?

An open container allows for the study of systems that are not completely isolated from the surroundings, such as living organisms or natural processes. It also allows for a more realistic representation of the system's behavior in real-life conditions.

What are the limitations of using a closed container for calorimetry?

One of the main limitations of a closed container is that it does not allow for any exchange of matter with the surroundings, which can be important in certain types of reactions or processes. It also requires precise and careful sealing to ensure no energy or matter is lost or gained during the experiment.

Can both closed and open containers be used for all types of calorimetry experiments?

No, the choice of using a closed or open container depends on the specific system being studied and the research objectives. Some experiments may require the use of both types of containers to obtain a comprehensive understanding of the system's behavior.

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