What makes ethanol flammable??
Answer:
C2H5OH(l) + 3O2(g) ---> 2CO2(g) + 3H2O(g)
The products here have a lower total energy than the reactants. This decrease in energy is seen in 2 things. An increase in the entropy of the system (liquid to gas and more randomized atoms) and an exothermic reaction. The Carbon is not in a fully oxidized state in ethanol and it is in CO2. The Carbon wants to have an oxidation state of +4 (as in CO2). In ethanol, it has an oxidation state of -2. Therefore, the Carbon is readily oxidized in the presence of O2 which is reduced to O^-2.
Water is the result of combustion reactions. The oxygen and the Hydrogens are both in their maximum reduced and oxidized form. H is +1 and O is -2. The O2 in the combustion would need to reduce the H in water back to H2, but O2 is an oxidizing agent. Therefore, this is not going to happen.
The ability of ethanol to combine with oxygen and burn.
Water cannot.
Because there is more chemical potential energy in ethanol than there is in water.
Water seeks its own level. What this means is that left to operate freely, all systems try and achieve the lowest energy state possible.
C2H5OH + 3O2 -> 2CO2 + 3H2O
Carbon dioxide and water are very low in chemical energy and it is not surprising that these two substances are the waste products of most reactions involving carbon and hydrogen.
three concerns: enthalpy, entropy and kinetics
enthalpy is favorable, as the kind folks above mentioned. also i would like to add that the products of combustions of EtOH have lower bond energy then the reactants.
entropy is favorable because the combustion reaction makes the system more disordered. Free energy is negative, hence the reaction is spontaneous.
kinetics. relatively low activation energy
Hydrogen is held more strongly by the Oxygen in water than it is by the Carbons in ethanol. When you heat water, it is difficult to separate the O and the H.
But when you heat ethanol, it is comparatively easy to separate the H from the C... and the H is flammable.
from structure of ethanol ,CH3CH2OH . Ethanol has an oxygen atom which has a high tendency of attracting bonding electrons of the carbon to which its attached . That carbon in turn draws electrons from the other carbon atom this weakens overall bonds in the molecule making it susceptible to attack by oxygen hence highly flammable. while the water molecule has strong bonds between the oxygen and the hydrogens hence limited susceptible to break up unless in presence of elements with stronger attraction for electrons than oxygen like fluorine than can water be flammable
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