Combustion of ethanol

Self-Test 6.14B Ethanol trapped in a gel is another common camping fuel. What mass of ethanol must be burned to supply 350. kj as heat The thermochemical equation for the combustion of ethanol is... 

The heat of combustion of ethanol (ethyl alcohol) is significantly lower than that of the saturated alkanes on a per gram basis. On a per mole basis, ethanol s heat of combustion is lower than those of all the saturated alkanes except methane. 

Combustion of propane C3H8 + 502 —> 3C02 + 4H20 Combustion of ethanol C2H5OH + 302 —> 2C02 + 3H20... 

When ethanol was substituted for propane, fewer moles of oxygen were required, but fewer moles of carbon dioxide and water were produced. The bond energies of the reactants decreased by (6486 kJ - 4726 kJ) = 1760 kJ, but the bond energies of the products decreased even more by (8498 kJ - 5974 kJ) = 2520 kJ. Therefore, we can deduce that the combustion of ethanol is less exothermic than that of propane and the other alkanes. 

Design an investigation to determine the enthalpy change of the combustion of ethanol using a wick-type burner, similar to that in a kerosene lamp. 

The DEFC transforms directly the Gibbs energy of combustion of ethanol into electricity, without a fuel processor. This greatly simplifies the system, reducing its volume and cost [22, 23]. The important development of DEFCs is due to the use of a proton exchange membrane as electrolyte, instead of a liquid add electrolyte, as done previously. 

The following results were obtained from an experiment carried out to measure the enthalpy of combustion (heat of combustion) of ethanol. The experiment involved heating a known volume of water with the flame from an ethanol burner. 

Hj. H = 1 C = 12 O = 16) f How much heat would be produced if 1 mole of ethanol had been burned (This is the heat of combustion of ethanol.) g Compare your value with the actual value of 1371 kj mol-1 and suggest two reasons for the difference in values. 

Combustion of ethanol in a small spirit lamp to demonstrate that it burns with a small blue flame. 

Hess s law is an extremely useful principle that helps us to determine the enthalpies of reaction for nearly any combination of materials. It states that for reactions that occur in different steps, the enthalpy of reaction is equal to the sum of the enthalpies for each step. Hess s law will allow us to calculate the enthalpy of reaction by using information about each reactant. In an example, let s consider the complete combustion of ethanol, C2H5OH, which is shown in the equation below ... 

If we want to determine the heat of reaction, where do we even begin The easiest place is to look at a measurement known as the standard enthalpy of formation, A H°f This is based on two different units, the enthalpy of formation, AHfi which represents the enthalpy change that occurs when a compound is formed from its constituent elements, and the standard enthalpy of reaction, AH0, which is the enthalpy for a reaction when all reactants and products are in their standard state (the state they exist in at 25°C and 1 atm). The standard enthalpy of formation is 1 mole of a compound from its constituent elements in their standard states. Enthalpies of formation can be found in many different reference books. Let s take a look at how we can use enthalpies of formation to determine the enthalpy of reaction for the combustion of ethanol. 

The combustion of ethanol has been studied between 270 and 370 °C by Cullis and Newitt [15—18]. At first, there is a period of some minutes during which no pressure change is discernible, although acetaldehyde is accumulating in the system [15]. When the acetaldehyde concentration reaches a critical level, the pressure begins to rise autocatalytically and methanol, formaldehyde and carbon monoxide become detectable [16]. 

Write and balance an equation for the combustion of ethanol (C2H5OH). 

The standard heat of combustion of ethanol at 25°C and 1 atm pressure is 328,000 cal/mole. The standard heat of combustion of acetaldehyde is... 

Some compounds, such as alcohols, are made of carbon, hydrogen, and oxygen. In the combustion of these compounds, carbon dioxide and water are still made. For example, the fuel known as gasohol is a mixture of gasoline and ethanol, an alcohol. The balanced chemical equation for the combustion of ethanol is shown below. 

The combustion of ethanol, C2HgO, produces carbon dioxide and water vapor. What equation best describes this process ... 

This calculation shows that for the combustion of ethanol at constant temperature and constant volume, the change in internal energy is —1365 kJ/mol ethanol. 

In Example 15-14 we found that the change in internal energy, AE, for the combustion of ethanol is —1365 kj/mol ethanol at 298 K. Combustion of one mole of ethanol at 298 K and constant pressure releases 1367 kj of heat. Therefore (see Section 15-5)... 

Equation stoichiometry problems have at their core the conversion of moles of one substance to moles of another substance. The conversion factor that accomplishes this part of the calculation comes from the coefficients in the balanced equation. Although we have not been given the balanced equation for the combustion of ethanol, we can supply it ourselves by remembering that when a hydrocarbon compound burns completely, all its carbon forms carbon dioxide, and all its hydrogen forms water. 

The enthalpy change that occurs in a chemical process depends upon the states of the reactants and products. Consider, for example, the complete combustion of ethanol, in... 

The combustion of other VOCs by perovskites, besides alkanes and alkenes, has also been investigated. Ling et al. [64] have studied LaNiOs catalysts for the combustion of ethanol and acetaldehyde, comparing activity of that for methane combustion. Oxidation of 1 vol.% VOC in air (total flow-100 ml min O.lg catalyst) followed the order for ease of combustion ... 

Reversing the reaction representing the combustion of ethanol gives ... 

---