Question
QUESTION THREE (20 MARKS) a) What do you understand by the term Gibbs free energy? Explain the physical meaning when its value is either negative or positive (3 Marks) b) What is an Ellingham diagram? What is it use in studying properties of materials (4 Marks) c) Discuss the processes involved in the thermal degradation of organic matter at atmospheric pressure (13 Marks) QUESTION FOUR (20 MARKS) a) What are the major highlights of the following types of diffusion i. Steady-state diffusion (5 Marks) ii. Non-steady-state diffusion (5 Marks) b) Explain the various factors that influence diffusion in materials (10 Marks) QUESTION FIVE (20 MARKS) a) Write short notes on: i) Reaction sintering ii) Solid Phase sintering (10 Marks) b) Discus at least ten major harmful effects of corrosion? (10 Marks)
Answer
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(346 Votes)
Luna
Master · Tutor for 5 years
Answer
a) Gibbs free energy is a thermodynamic potential that can be used to calculate the maximum reversible work that may be performed by a system at constant temperature and pressure. A negative value means the reaction is spontaneous, while a positive value indicates it is non-spontaneous. b) An Ellingham diagram is a graph showing the temperature dependence of the stability of compounds. It is used to predict the direction of a metallurgical reaction in the field of metallurgy and materials science. c) The thermal degradation of organic matter at atmospheric pressure involves the process of pyrolysis. The organic material is decomposed by heat into gases, liquids, and solid residue. a) Steady-state diffusion refers to the process where the concentration of diffusing species does not change with time. Non-steady-state diffusion occurs when the concentration does change with time.b) Factors that influence diffusion in materials include temperature, concentration gradient, type of material, and the size of the diffusing species.a) Reaction sintering is a method used in the production of ceramic materials where a reaction between the raw materials takes place during the sintering process. Solid Phase sintering is a type of sintering where the solid state reactions and mass transport between the initial components take place.b) Corrosion can cause several harmful effects including material loss and failure, contamination, environmental damage, and health hazards.
Explanation
a) The Gibbs free energy is a measure of the potential for reversible or maximum work that a system can do. A reaction is considered spontaneous if the Gibbs free energy is negative, as the system is releasing energy. If it's positive, the system requires energy for the reaction to occur.b) An Ellingham diagram is a tool used in the study of thermodynamics. It allows us to understand the temperature dependence of the stability of compounds. It's particularly useful in predicting the outcomes of reactions in metallurgy.c) Thermal degradation of organic matter, or pyrolysis, involves the organic matter being broken down by heat into gases, a liquid, and a solid residue. This occurs without the presence of oxygen. The process is used in a variety of applications from energy production to waste disposal.a) Steady-state diffusion occurs when the concentration of the diffusing species remains constant over time, while non-steady-state diffusion is when the concentration changes over time.b) Several factors can influence diffusion. These include the temperature (higher temperatures increase diffusion), the concentration gradient (greater differences in concentration can increase the rate of diffusion), the type of material (certain materials allow for faster diffusion), and the size of the diffusing species (smaller particles diffuse faster).a) Reaction sintering is a method of producing ceramics that involves a reaction between the raw materials during sintering. Solid phase sintering, on the other hand, involves reactions and mass transport between the initial components.b) Corrosion can have a variety of harmful effects. It can cause material loss and structural failure, can contaminate products and environments, can cause environmental damage (such as pollution), and can pose health hazards (such as from the inhalation of corroded materials).