Ethanol Rocket: Difference between revisions
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The volume-% of oxygen in air is 20.9%. The volume of the bottle is <math>V = 500 </math> ml which gives the amount of oxygen to be <math>0.209 V = 0.209 \times 500 = 104.5</math> ml <math>=0.1045\times1.314 = 0.137 </math> g of oxygen, which gives the amount of ethanol <math>0.137 / 2.1 = 0.0659 </math> g <math>=0.0659/0.789= 0.0834</math> ml. '''OR''' directly using air--ethanol ratio we have <math>\rho V/9 = 1.2041 \times 0.5 /9 = 0.066</math> gram. That amount equals to <math>V/\rho_\textrm{Ethanol} = 0.066g/(789g/l) = 0.084 </math> ml <math>=84 </math>mm<sup>3</sup>. Almost the same result using the methods. See the attached spreadsheet for detailed calculations. | The volume-% of oxygen in air is 20.9%. The volume of the bottle is <math>V = 500 </math> ml which gives the amount of oxygen to be <math>0.209 V = 0.209 \times 500 = 104.5</math> ml <math>=0.1045\times1.314 = 0.137 </math> g of oxygen, which gives the amount of ethanol <math>0.137 / 2.1 = 0.0659 </math> g <math>=0.0659/0.789= 0.0834</math> ml. '''OR''' directly using air--ethanol ratio we have <math>\rho V/9 = 1.2041 \times 0.5 /9 = 0.066</math> gram. That amount equals to <math>V/\rho_\textrm{Ethanol} = 0.066g/(789g/l) = 0.084 </math> ml <math>=84 </math>mm<sup>3</sup>. Almost the same result using the methods. See the attached spreadsheet for detailed calculations. | ||
{| class="wikitable" | {| class="wikitable" | ||
|+ | |+ Densities | ||
|- | |- | ||
! !! Density <math>\rho</math>!! At | ! !! Density <math>\rho</math>!! At | ||
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The inner diameter of the rocket bottle is 25 mm. The height of the ethanol in the cap need to be <math> V = \pi r^2 h \iff h = \frac{V}{\pi r^2} = \frac{84 mm^3 }{ \pi 12.5^2 mm^2} = 0.17 </math> mm. | The inner diameter of the rocket bottle is 25 mm. The height of the ethanol in the cap need to be <math> V = \pi r^2 h \iff h = \frac{V}{\pi r^2} = \frac{84 mm^3 }{ \pi 12.5^2 mm^2} = 0.17 </math> mm. | ||
=== Piezo Crystal === | === Piezo Crystal === | ||
Revision as of 22:04, 29 May 2021
Introduction
Theory
Ethanol 3d model
| -1.1712 | 0.2997 | 0.0000 | O |
| -0.0463 | -0.5665 | 0.0000 | C |
| 1.2175 | 0.2668 | 0.0000 | C |
| -0.0958 | -1.2120 | 0.8819 | H |
| -0.0952 | -1.1938 | -0.8946 | H |
| 2.1050 | -0.3720 | -0.0177 | H |
| 1.2426 | 0.9307 | -0.8704 | H |
| 1.2616 | 0.9052 | 0.8886 | H |
| -1.1291 | 0.8364 | 0.8099 | H |
HCH bonds are assumed to be undistorded tetraherdal angle 109.5 degrees. Actually the electrons repeal each other. The HOC bond is 104.5 deg because. . .
Valence shell electron-pair repulsion theory (VSEPR theory). . .
| Atom | Radius | |
|---|---|---|
| C | 170 pm | 1.42 |
| H | 120 pm | 1.00 |
| O | 152 pm | 1.27 |
Use CPK coloring convention, white (hydrogen), black (carbon) and red (oxygen).
Ethanol reaction with Oxygen and Air
Ethanol reaction with oxygen
The molecular weight of ethanol is g/mol, and the molar weight of oxygen is 32 g/mol. The oxygen--ethanol fuel ratio is . We need kg of oxygen to kg of ethanol. The air consists of 23.2 mass-% of oxygen, thus the air--ethanol ratio is .
The volume-% of oxygen in air is 20.9%. The volume of the bottle is ml which gives the amount of oxygen to be ml g of oxygen, which gives the amount of ethanol g ml. OR directly using air--ethanol ratio we have gram. That amount equals to ml mm3. Almost the same result using the methods. See the attached spreadsheet for detailed calculations.
| Density | At | |
|---|---|---|
| Oxygen (g) | 1.429 g/l | STP |
| Oxygen (g) | 1.314 g/l | 20 °C |
| Ethanol (l) | 789.45 g/l | 20 °C |
| Air (l) | 1.2041 g/l | 20 °C |
File:Ethanol oxygen combustion.ods
The inner diameter of the rocket bottle is 25 mm. The height of the ethanol in the cap need to be mm.
Piezo Crystal
To ignite the air--ethanol mixture, we use piezo crystal. When tjhe piezo crystal is compressed, it will generate an electric charge which creates a spark.
References
https://nptel.ac.in/content/storage2/courses/123106002/MODULE%20-%20I/Lecture%201.pdf
