Ethanol Rocket: Difference between revisions

From wikiluntti
VisualWikitext
Line 57: Line 57:
The molecular weight of ethanol is <math>46.069</math> g/mol, and the molar weight of oxygen is 32 g/mol. The oxygen--ethanol fuel ratio is <math>3\times 32 / 46 = 2.1</math>. We need <math>2.1 </math> kg of oxygen to <math>1</math> kg of ethanol. The air consists of 23.2 mass-% of oxygen, thus the air--ethanol ratio is <math>2.1/0.232 = 9</math>.  
The molecular weight of ethanol is <math>46.069</math> g/mol, and the molar weight of oxygen is 32 g/mol. The oxygen--ethanol fuel ratio is <math>3\times 32 / 46 = 2.1</math>. We need <math>2.1 </math> kg of oxygen to <math>1</math> kg of ethanol. The air consists of 23.2 mass-% of oxygen, thus the air--ethanol ratio is <math>2.1/0.232 = 9</math>.  


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\times1.429 = 0.149 </math> g of oxygen, which gives the amount of ethanol <math>0.126 / 2.1 = 0.072 </math> g <math>=0.072/0.789= 0.091</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. Almost the same result. See the attached spreadsheet for detailed calculations (and mistakes).  The small difference in amounts is due to the density of oxygen, which is at STP (0 degrees).  
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. Almost the same result using the methods. See the attached spreadsheet for detailed calculations.
 
[[File:Ethanol oxygen combustion.ods|thumb|Ethanol oxygen combustion spreadsheet]]
 
 
 
The density of oxygen
 
{| class="wikitable"
{| class="wikitable"
|+ Caption text
|+ Caption text
Line 78: Line 71:
| Air (l) ||1.2041 g/l|| 20 °C  
| Air (l) ||1.2041 g/l|| 20 °C  
|}
|}
[[File:Ethanol oxygen combustion.ods|thumb|Ethanol oxygen combustion spreadsheet]]


== References ==
== References ==

Revision as of 20:25, 29 May 2021

Introduction

Theory

Ethanol 3d model

Atom positions
-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). . .


Van der Waals radius
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

Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \textrm{C}_2 \textrm H_6 \textrm O + 3\textrm O_2 \to 2 \textrm{CO}_2 + 3 \textrm H_2\textrm O }

The molecular weight of ethanol is Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 46.069} g/mol, and the molar weight of oxygen is 32 g/mol. The oxygen--ethanol fuel ratio is Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 3\times 32 / 46 = 2.1} . 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 Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle V/\rho_\textrm{Ethanol} = 0.066g/(789g/l) = 0.084 } ml. Almost the same result using the methods. See the attached spreadsheet for detailed calculations.

Caption text
Density Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle \rho} 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

References

https://nptel.ac.in/content/storage2/courses/123106002/MODULE%20-%20I/Lecture%201.pdf

https://www.peacesoftware.de/einigewerte/o2_e.html

Retrieved from "https://wiki.luntti.net/index.php?title=Ethanol_Rocket&oldid=4606"