A member of the U.S. Congress proposed a scheme to produce energy as follows. Water molecules (H2O) are to be broken apart to produce hydrogen and oxygen. The hydrogen is then burned (that is, combined with oxygen), releasing energy in the process. The only product of this combustion is water, so there is no pollution. In light of the second law of thermodynamics, what do you think of this energy-producing scheme?
Solution 5DQ Introduction We have to think in terms of total energy output from the whole process to see if it is possible to generate in the process. Solution According the to second law of thermodynamics, it is not possible to get work done from an engine if the engine can take heat from hot reservoir and release heat in the colder shink. Now the process discussed in the above process we are starting from some state (liquid water) and finally returning to the same state. Hence the engine is working between the same state and hence between same temperature, hence according to the second law of thermodynamics it is not possible to get any net work done (or energy) from the engine. In other words we can say that the supplied energy in one half of the cycle will be equal to the available energy on the other half of the cycle. So the energy producing scheme, as proposed by the congressman, will not work.
