Enthalpy Changes of Combustion of Different Alcohols
Aim:
The aim of this experiment is to find out how the enthalpy change
(total energy released when the alcohols are completely combusted in a
plentiful supply of air) for 5 different alcohols is affected by the
number of carbon atoms in the alcohol and other factors contributing
to the molecular structure.
Prediction:
I predict that as the amount of carbon atoms in the alcohol increases,
the higher the enthalpy of combustion will be. I have made this
prediction, using the values for the enthalpy change of combustion for
each alcohol, calculated using bond enthalpies and Hess' law.
Methanol's molecular formula is CH3OH. This is the basic structure for
all the alcohols, then to make the larger ones an extra carbon is
added to the existing carbon each time and the oxygen-hydrogen
molecule gets added to the atoms added to the new carbon atom
When methanol combusts in air, it reacts with oxygen molecules to from
water and carbon dioxide. The balanced equation fort this is:
[IMAGE] CH3OH (l) + 1.5O2 (g) CO2 (g) + 2H2O (l)
This means that the bonds broken are; 3 carbon- hydrogen, 1
carbon-oxygen, 1 oxygen-hydrogen and 1.5 oxygen- oxygen (double bond)
and the bonds broken are; 2 carbon- oxygen (double bond) and 4
oxygen-hydrogen.
Constructing a Hess' law cycle will show how these are linked
together:
[IMAGE] CH3OH (l) + 1.5O2 (g) CO2 (g) + 2H2O (l)
[IMAGE][IMAGE]
C (g) + 4H (g) + 4O (g)
N.B. bond enthalpies are for elements in their gaseous states
If a calculation for the amount of energy needed to break the bonds is
made and then the amount of energy given out from bond formation, the
resultant energy difference (negative because the reaction is
exothermic) is the enthalpy change of combustion.
Average bond enthalpies for elements in their gaseous states
(kJmol-1):
Carbon - Carbon (C-C) = +347
Carbon - Hydrogen (C-H) = +413
Oxygen - Hydrogen (O-H) = +464
The Armenian genocide ruins Vahan Kenderian’s picture-perfect life. Vahan is the son of the richest Armenian in Turkey and before the war begins, he always has food in his belly and a roof over his head in the book Forgotten Fire by Adam Bagdasarian. Life is absolutely quintessential for Vahan, until the war starts in 1915, when he endures many deaths of his family, losses of his friends, and frightening experiences in a short amount of time. He is a prisoner of war early in the book and is starved for days. As he goes through life, he is very unlucky and experiences other deaths, not just the deaths of his family. Vahan ultimately becomes the man his family would want him to be.
Catching Fire: How Coooking Made us Human by Richard Wrangham is a fresh perspective on the evolution of humankind. Wrangham has made a concentrated effort to prove that humans have evolved particular adaptations, like bipedalism, due to the introduction of cooked foods into their diet. In his book, he is legitimately arguing that humans are the way they are because early on in human evolution, early man discovered fire, discovered the joys of cooked foods, and developed all sorts of fascinating traits still being utilized today.
Text Box: CaCO3 + HCl = CaCl2 + CO2 + H2O calcium carbonate + hydrochloric acid = calcium chloride + carbon dioxide + water
Experiment to Find Out Which Fuel Produces Most Energy. Aim = == My objective in this piece of coursework is to determine which of five fuels produces the most energy and if the energy production relates to the amount of carbon..
CaCl2 + H2O + CO2
Investigation of the heat energy produced by combustion of various alcohols. Aim: ---- To investigate how different alcohols produce different amounts of heat energy through combustion. I will be heating water using different alcohols as fuels and measuring the amount of fuel consumed.
one gram of water by 1ºC. I chose to use water because it is safe,
the same will be the height of the tin can above the wick. I will keep
-2152.7 x (56.1 / 1.37) = -88150.7 J.mol. 1. H = -88.15 kJ.mol. Hess' law states that: 1"The total enthalpy change for a chemical reaction is independent of the route by which the reaction takes place, provided initial and final conditions are the same.
The Enthalpy Change of Different Alcohols My aim is to compare the enthalpy change of combustion of different alcohols in relation to the structure of each molecule. The enthalpy change of combustion of a fuel is a measure of the energy transferred when one mole of the fuel burns completely. In a chemical reaction, bonds must either be made or broken, this involves an enthalpy change. The formation of bonds is exothermic, energy is lost to the surrounding; on the other hand, breaking bonds is endothermic, energy is taken in. I obtain the value for the enthalpy change of each fuel by using the formula: Energy transferred from the fuel=
from both sides, leaving us with ½ V2 = GH. When the above equation is
Investigating Factors Affecting the Heat of Combustion of Alcohols PLANNING SECTION Introduction ------------ Alcohols are organic substances, and consist of Hydrogen, Oxygen and Carbon. All alcohols are toxic but the amount that can be tolerated by the human body varies for different alcohols. For example drinking small amounts of Methanol can lead to blindness and even death.
Chemistry Aim- To determine the enthalpy change for the reaction of copper sulphate and zinc. Materials Required- Calorimeter Glass Thermometer Weighing Machine Digital Stop Watch Measuring Cylinder Cuso4. 5H2o Zinc Metal Powder Distilled Water.
When gasoline burns in the engine of a car, an equal amount of work and heat appears as the energy is released. The heat from the engine warms its surroundings, the car parts, the air, and the passenger area. The heat energy is converted into the electrical energy of the radio, chemical energy of the battery, and radiant energy of the lights. The change in the sum of all of the energies formed from the burnt gasoline is equal to the “.change in energy between the reactants and products.” Biological processes, like photosynthesis, also follow energy conservation.
Pyrolysis is a rapid thermal decomposition process of organic biomass, in absence or little supply of oxygen, brought about by high temperatures into useful biofuel products such as pyrolysis oil, ethanol, biodiesel, methanol etc. During the process, large hydrocarbon molecule’s chemical composition structure breaks down into relatively smaller molecules into solid (char), liquid or gas phase (Figure 1). The process is very similar to many other biomass decomposition processes such as torrefaction, carbonization, devolatilization etc. however pyrolysis cannot be compared to gasification due to external activation required for gasification.