Reflection
assallamualaikum w.b.t to Dr Asnizam Abu Bakar...this is my second reflection journal...several week ago i learnt about thermodynamics...the first chapter that i learnt was second law of thermodynamics..in this chapter i learnt new things about heat engines,refrigerators and heat pumps and the carnot cycle...we must have high level of understanding..even though i do many exercise my understanding was not enough...after that i learnt about entropy...the most difficult chapter i want to understand...in this chapter, the first thing that we must know was is exactly entropy....unfortunately according to yunus a cengel in his book...he said that they cannot give an adequate answer to this question...this term "enrtropy" was same with energy...i also learnt about entropy change of pure subtances, liquids n solid and enropy change in ideal gas....to find entropy change they have their own formula that we must remember..then i learnt about isentropic...the thing that i understand in isentropic was the enropy change was equal to zero...that mean the si=s2....isentropic also means adiabatic and reversible...after that i learnt about isentopic efficiencies of steady flow devices such as turbines, compressors and pumps...to answer question that related with this subtopics we must know how to sketch the T-s diagram to illustrate what happen during the process....finally i learnt about entropy balance...the most important thing i learnt in this subtopic was to find Sgen to determine if the process was impossible or not...thank you that all know...assallamualaikum...
assallamualaikum to Dr. Asnizam bin Abu Bakar.. im very sorry because i just do my reflection journal but i trying to remember what lesson that u teach me... for the first time u enter your class, i think that u so strict but after several class i think u so funny and kind to u students....the first lesson that he teach me was about energy balance which is balances on nonreactive process.. he teach his students until his students understand what he trying to teach us..he give many exercise to us so that we can more understand...in this chapter i learned about the references state,the hypothetical energy balance, and many more..after that we have test 1 ...this test 1 was about this chapter...i was frust about my first result because i just got 50 over 100...i thought by doing many exercise i can answered all the question but for the question no 3 and 4 i fail to answered it..mybe i not have enough understanding about this chapter...eventhough doctor always teach us about the concept..after that, we study about the next chapter which is balances on reactive process...in this chapter , to determine heat of reaction we have three method which is hess law,heat of formation, and heat of combustion..the easiest method was hess law and heat of formation...next we learned about energy balances on reactive process, there are two method to find the value of enthalphy which are heat of reaction method and heat of formation method...DR Asnizam prefer tu us to use heat of formation since heat of formation was more easiest to use...the first thing to do heat of formation was to complete the mass balance and use the information given as much as possible..then, prepare the inlet entalphy table and must remember to write the references state..the references state was based on the elemental species that found in the equation at 25 C...After that solve like always,hahaa...i lazy to write anymore...so that is for today...will be continued,hehe
The first day I was so excited to learn new thing , but somehow I doubt that the subject is quite hard for me. Its not the first time I heard this subject because in 1st semester I already heard this subject from senior and they said that the subject quite though for engineering student. When I heard that, I was so afraid that I cant score this subject because in 1st semester I never learn about chemical equation as I should be because I like chemistry subject. Besides, this subject was 3 credit hours and will effect our result if we do not score. In the first day of Principle of Chemistry class, or popular name is mass balance we were briefed by Dr. Ramli Mat. He is my lecturer until this subject ended . We have been advised to master all the chapter that we learn in the 1st semester that is Introduction to Engineering. In this topic, all the calculation that we learn from the 1st semester we used in this subject such as convertion unit and others. he advised me to be competent in the conversion unit because it is very important to mass balance subject. Dr. Ramli Mat tought us a new technique for conversion unit and make it simple. So, we did not waste our time to do a long calculation for conversion unit in chapter 1,2 and 3. In week 1, we only learned chapter 1 until 3 which was basic for mass balance subject.
In week 2 until week 8, i started to learn the actual things for this subject in chapter 4 the fundamentals of material balances. In this chapter, we needed to draw the system boundaries for which the material balance is to be made and must differentiate an open and closed system. we learned material balance equations and flow chart. Dr. Ramli Mat always told us do the flowchart before doing the calculation and then consider the state the process in steady state, semi batch and continous process. Basis played the main role to do the calculation because i need to have basis before start teh calculation. Basis can be in mass, volume, mass flowrate and volume flowrate. Every single thing i learn is operating at steady state when variable in a process are do not change with time and unsteady state for variable changing with time. I must be careful because there are big different between steady state and unsteady state. we also need to understand how to solve the equation by using simoltaneous equation based on the flowchart that we had draw. Before that, we must calculate the degree of freedom to make sure we can solve the equations. . It quite challenging to solve the equation because there are many things to consider and to many technique to do it. The thing is if we understood the the question so we can solve it easily like abc. But as for me, i did not understand the question and a lot of things mybe i do not know. Furthermore , I learn about the stoichiometry equation, stoichiometry ration, stoichiometry proportion, limiting and excess reactants, fractional excess, fractional conversion and extent of the reaction. This equation is important to deal in reactive chemical equilibrium equation. For reactive process there are three process that are using molecular, atomic and extent of reaction. The most easy was using the atomic spesies because only consider input and output. Last topic in chapter 5 is combustion reaction. This topic was quite simple but need to understand the concept for example percentage of excess air. In test 3, this kind of questions coming out and i think i can do it.
In week 9, i learned the single phase system in chapter 5. This chapter is about liquid and solid densities, ideal gas, standard temperature and pressure, ideal gas mixture, equation of states for non- ideal gases, and compressibility factor equation of state for non- ideal gases. I already learn the ideal gas law during matriculation but this time i learn more details on the ideal gas and non- ideal gases. Dr Ramli Mat gave all the tips how to answer the questions in this chapter. He said that need to know how to convert unit and know the condition of gas where its ideal or non- ideal. This chapter have a lot of formulas and we must how to use it. For example, we need to calculate the reduced temperature, reduced pressure and reduced volume for real gas law and use compressibilty charts to obtain the compressibility factor.
In week 10 until 11, i learn about mutil-phase system which include single-component phase equilibrium, the gibbs phase rule, one condensable component and multicomponent gas-liquid system. In this chapter, we need to apply raoult's Law for single condensable species, explain the meaning of ideal solution and the applicability of henry's law and roult's law and lastly know how to use Txy and Pxy diagram to determine the bubble compositions and relative amounts of each phase in a two phase mixture and the effects of varying temperature and pressure on bubble point, dew point, and phase amounts and compositions. As for me, this chapter is quite hard for because we really the understand the concept of SCS and multi. if we did not understand the concept maybe we can't solve the questions and need a lot of time to solve. Lastly, week 12 until 14 i learn the energy balance for closed and open system. To solve the question on this topic we need to look the table behind the priciple's book then get the data and solve it. I do not understand this chapter very well because i did not focus in the class. The last class, i have the evaluation for single and mutiple system. The evaluation is to determine wether we can solve the questions or not based on 10-step strategies.