The Second Law of Thermodynamics relates the heat associated with a process to the entropy change for that process. Therefore as a redox reaction proceeds there is a heat change related to the extent of the reaction, dq/dξ = T(dS/dξ).

Why is the second law of thermodynamics so important? Second law of thermodynamics is very important because it talks about entropy and as we have discussed, ‘entropy dictates whether or not a process or a reaction is going to be spontaneous’.

But the new experiment probed the uncertain middle ground between extremely small-scale systems and macroscopic systems and showed that the second law can also be consistently broken at micron scale, over time periods of up to two seconds.

What are the applications of the second law of thermodynamics? 1) According to the law, heat always flows from a body at a higher temperature to a body at the lower temperature. This law is applicable to all types of heat engine cycles including Otto, Diesel, etc. for all types of working fluids used in the engines.

Think of two scenarios: cooking on a stove and driving. Explain how the second law of thermodynamics applies to these two scenarios. While cooking, food is heating up on the stove, but not all of the heat goes to cooking the food, some of it is lost as heat energy to the surrounding air, increasing entropy.

The most common practical application of the First Law is the heat engine. Heat engines convert thermal energy into mechanical energy and vice versa. Most heat engines fall into the category of open systems.

The first law of thermodynamics deals with the total amount of energy in the universe. It states that this total amount of energy is constant. The challenge for all living organisms is to obtain energy from their surroundings in forms that they can transfer or transform into usable energy to do work.

Open thermodynamic system. We begin with the first law of thermodynamics applied to an open thermodynamic system. As illustrated in Fig. 1, an open system allows mass and energy to flow into or out of the system.

specific heat constants

The Cp/Cv ratio is also called the heat capacity ratio. In thermodynamics, the heat capacity ratio is known as the adiabatic index. Cp/Cv ratio is defined as the ratio of two specific heat capacities. (i.e.) Heat Capacity ratio = Cp/Cv = Heat capacity at constant pressure/ Heat capacity at constant volume.

Steam Cp=1.8723 kJ/kg. K Cv=1.4108 kJ/kg. K – see steam tables. At IUPAC standard temperature and pressure (0 °C and 101.325 kPa), dry air has a density of 1.2754 kg/m3.

Show that Cp – Cv = R. Consider one mole of an ideal gas enclosed in a cylinder fitted with movable frictionless piston. Let the gas be heated at constant volume first. Let the temperature of the gas increase by dT when dQ quantity of heat is supplied.