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al zami

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  1. why after throtlling steam gets superheated???any explanation???
  2. adibetic curve in pv will become isentropic curve in ts. then in Ts what will be the constant pressure curve of pv ??
  3. what is the relation between pv and ts diagram.what i trying to say is if a pv diagram is given then how can i assume the ts diagram from it?????
  4. sorry for the delay. been too busy for exam it becomes impossible to make time to visit the forum. ok that gives the intuation . as entropy means energy is used and we are not getting the energy back.so entropy is increasing. previously you compered entropy with voltage difference.as we know voltage difference helps to move electrons from lower to higher voltage.does entropy do similar or such thing.i mean does entropy is responsible for the flow of something.if not then from where this comparison is derived from ????
  5. i didnt get the question.sorry for that.i dont know the answer.if i dont give answer to your questions i am sorry for that.entropy is not in my syllabus.i know maths will lead to better understanding.but classes are going in a full swing and its hard to make time for out of the syllabus topics.the basic thing which i wanted to know from where the formula dQ/T came from and what it signifies???what leads the scientists to introduce a concept like ENTROPY??? dQ/T is always greater than or equal zero .it is said to be the fundamental law of the universe.entropy was not in my syllabus.i am trying to understand the topic because i have admiration towards astronomy and trying to understand the facts.if we freeze water entropy is negative.why this shows contradiction to dQ/T>=0;
  6. actually i am not worried about calculations.i am trying to grab the concept.entropy of each thermodynamic process is always equal or greater than zero.if i melt ice that will increase entropy .and if in regain ice from water that should increase entropy too.how this happen ??
  7. temp for melting q1=m*lf =1*2100 temp for taking the temp upto 20 degree =m*c*t =1*4200*20 total heat q=q1+q2 here q is the enthalpy entropy S=intrigating q/T within 0 to 20 and s is the entropy isn't that right? actually i tried to say if i put a piece of ice in water and let it melt .we cant get the exact piece of ice back from the water.if we freeze the water then the the whole water will turn into ice .but the exact piece can't be brought back,in that case it is irreversible s=q/dT means heat added per degree of temperature change.how this is related to the terms "disorder" or with "arrow of time" such types of concepts ??????
  8. it confuses me.this is the amount of heat taken for melting.here entropy changes because the molecules of ice gets disordered and gets mixed in water,and we cant get the actual amount ice back from melted ice and water mixture,isn't it?its irreversible but if we apply this equation for entropy change s=q/T then we get s=q/0 [temp at o degree] s=undetermined doesn't making any sense.
  9. i dont understand the question.is it water and ice are in same container or in seperate container?? and what is the mass of ice .as i need it to calculate latent heat m*lf
  10. you've said It contains more than just heat transferred but if it is constant pressure process then we can say h=u+pdv =>h=q-w+pdv =>h=q-pdv+pdv =>h=q so here enthalpy change is equal to heat transferred,isn't it??,But in adiabatic process we cant say enthalpy depends only on heat added. consider two system where one has volume two tymes than the other one but of same temperature then we can say the larger system has more heat content than the other one .so we can say the larger system has more entropy than the small one??? but can we say the larger one has more enthalpy than the small one????so if we can or can't then what is the difference between these two terms ???? and what is the difference between enthalpy change and entropy change?and what physical phenomena these two terms describe about a system .?
  11. thanks !but for w=F*x means because of F force a particle covers x distance .here i can measure the force and distance x . in here q=Tds because of temperature T .......... what can i say in the dash to make it a perfect definition for q as i did it for work done w. and if so , what is the difference between entropy and enthalpy
  12. what is meant by this example???it is not clear to me ?can you explain this to me?? thanks!it clears the mathemetical part.i wanted to know the actual meaning of increasing and decreasing entropy?what happens when entropy increase or decrease?how it is related to heat content and temperature??
  13. what this equation means h=hf+x*hfg what is the physical meaning of dryness fraction.
  14. actually how can i physically define entropy??? i know that change in position.disorder etc means there is a change in entropy,isn't it?
  15. why adiabatic process is called isentropic. we know disorder or any change makes entropy to change.then how adiabatic process keeps entropy constant .a clear explanation will be appreciated.
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