1) Define the four laws of thermodynamics using words, diagrams and equations where appropriate. a). Zeroth Law of Thermodynamics which deals with the thermal equilibrium and states, if two Thermodynamic systems are separately in thermal equilibrium with a third, they are also in thermal equilibrium with each other. The law implies that the thermal equilibrium in the Thermodynamic systems is an equivalence relations between the systems as studied under these systems. Methamatical equation for the law is represented with the use of symbols T=Temperatue, and A, B and C are the three systems and the equivalence relation among all these systems is give below: If T(A)= T(B), if T(B)= T(C), Then T(A)= T(C)b).
First law of Thermodynamics is about the conservation of energy and states, “The change in the internal energy of a closed system is equal to the sum of the amount of energy supplied in the form of heat and the work done on the system”. Equation: Du= δQ- Δwwhere δQ is a small amount of heat added to the system, dU is a small increase in the internal energy of the system, and δW is the small amount of work done by the system during the operations of the system. c).
The second law of Thermodynamics is about entropy and states that the entropy of an isolated system which is not in equilibrium will tend to increase over time, and approaching to a maximum value at equilibrium. d). The third law of Thermodynamics is a statistical law which states as under: 2) What is entropy? Explain what happens to the motion of water molecules when ice melts into water? What happens to the entropy in this situation? (2 marks)Answer: Entropy is a measure dealing with the disorder of a system.
The concept is applied to the systems as studied in Physics, Mathematics and Chemistry regarding the behavior of the molecules during energy changes and transfer of heat during the operations of the systems. When ice melts into water molecules, the system absorb heat from the surroundings and therefore their motion increases. Entropy increases in this position. 3) Calculate ΔS for the following reaction, using the information in a Table of Thermo chemical Data, and state whether entropy increases (becomes more random) or decreases (becomes less random)?
Based on entropy changes, do you predict a spontaneous reaction? 2 NO (g) + O2 (g) →N2O4 (g) Answer: For the equation 2 NO (g) + O2 (g) →N2O4 (g), ΔS= Δq /T where Δq= +155.65 kJ and T = 273, so. ΔS= Δq /T =155.65/273 =0.57 kJ at the temperature absolute zero. Based on the entropy change a spontaneous reaction between the reactants is predicted as the system will react to establish a relationship on the basis of any change in the entropy.
4) These questions test your understanding of temperature measurements and temperature scales. i) What is absolute zero on the Kelivin, Celsius, Fahrenheit and Rankine scales? ii) The boiling point of water if 100°C what is this in Kelvins? iii) The temperature of a system rises by 30°C during a heating process. Express this rise in temperature in Kelvins. iv) The temperature of a system rises by 60°F during a heating process. Express this rise in temperature in R, K and °C.