Amount of energy required to split zinc-oxide

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Discussion Overview

The discussion centers on the energy required to split zinc oxide (ZnO) into zinc and oxygen, particularly at high temperatures such as 2500 degrees Celsius. Participants explore the implications of temperature on the energy needed for this process, including theoretical calculations and the physical state of ZnO at elevated temperatures.

Discussion Character

  • Exploratory
  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant inquires about the feasibility of splitting ZnO at 2500 degrees Celsius and whether this high temperature reduces the energy requirement for separation.
  • Another participant asserts that heating ZnO to such high temperatures provides energy that helps overcome the electrostatic forces between zinc and oxygen ions, suggesting that less energy is needed compared to room temperature.
  • A different participant asks for the specific temperature required for splitting ZnO and whether the energy needed for electrolysis decreases with temperature.
  • One participant mentions that the boiling point of ZnO is 2360 degrees Celsius, indicating that at this temperature, the ionic structure is destroyed, allowing zinc and oxygen to escape, thus achieving separation.
  • This participant also notes the absence of specific calculated values for the heat of vaporization of ZnO, but provides a theoretical calculation for the energy required to convert ZnO from solid to gaseous ions at 25 degrees Celsius, including heat capacity and lattice energy considerations.

Areas of Agreement / Disagreement

Participants express varying views on the energy dynamics involved in splitting ZnO at high temperatures. While some agree that high temperatures reduce energy requirements, others raise questions about specific temperatures and calculations, indicating that the discussion remains unresolved.

Contextual Notes

There are limitations in the discussion regarding the lack of specific values for heat of vaporization for ZnO and the assumptions made in the calculations presented. The calculations rely on theoretical values and conditions that may not reflect practical scenarios.

goleynik
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How could I split zinc-oxide into zinc and oxygen? The zinc-oxide would be at 2500 degrees Celsius. Because it is as such a high temperature, would that reduce the amount of energy that I would need to put into separate the two?

Thanks!
 
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Yes, definitely.

When the substance is heated up such high temperature, they already gain a substantial amount of energy from the the heating process. The energy is used to overcome the electrostatic force of attraction between the Zinc ions and Oxygen ions.

If you are comparing between the required energy to break the bond between Zn and O at room temperature and at 2500 C, you would definitely need to put in more energy in the case of room temperature. This is because at 2500 C, the substance already possesses more energy that is used to break the bond.
 
What temperature would it have to get to split. Also would the amount of energy to electrolyze it decrease because of the temperature?
 
The boiling point of Zinc Oxide is 2360 degree C. At this temperature, the ionic structure is completely destroyed, Zinc and Oxygen ions will escape. With this, the Zinc and Oxygen can be said to have been 'split'.

Well, through my research, there is no specific calculated values for heat of vaporisation for ZnO. As such, I cannot possibly calculate for you the value of energy required for ZnO to be 'split' due to vaporisation. However, there is calculation values for conversion to Zn2+ and O2- ions at 25 degree C (298K), which not likely to happen in reality. I will show it to you anyway.

ZnO(s) [2000 C] → ZnO(s) [25 C] → Zn2+(g) + O2-(g) [25 C]

The calculation of the the energy to split will be as follow:

1) The temperature of ZnO solid at 2000 C will be lowered to 25 C

Heat Capacity: 40.3 J/(mol K) (http://chemicals.etacude.com/z/zinc_oxide.php)

ΔHrxn = -40.3 x (2000-25) = -79600 J/mol

2) The ZnO solid is split into gasous ions at 25 C

Lattice energy of ZnO at 25 C: 4142 kJ/mol (http://www.webelements.com/zinc/lattice_energies.html )

3) Overall ΔH = -796000 + 4142 = -75450kJ/mol



Hope that will help to satiate your curiosity.
 
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