sign conventions in thermodynamics?

Question

What are the sign conventions of work done by the system in thermodynamics?

Answer 1

An exothermic reaction has a negative delta H value. (The system has lost energy to the surroundings.) (It has done work on the surroundings.)

An endothermic reaction has a positive delta H value. (The system has gained energy from the surroundings). (The surroundings have done work on the system.)

Answer 2

hi Smiles(might the percentages be ever your desire!), definite such diverse conventions do ensue in physics and chemistry books even in state boards. some how we could continually persist with some handy ones with the intention to remedy issues easily. case in point: In physics that's suggested that the circuit is CLOSED whilst that's in ON place. yet in chemistry that's in any different case. The circuit is declared to be OPEN whilst that's in ON place. comparable way destructive and constructive sign convention in regards to the paintings performed. truly we could continually comprehend in regards to the sign convention. If the observer (doer) does paintings on the gadget then observer's paintings must be seen as +ve and if the gadget does paintings then it must be taken to be -ve. the main reason is that as observer does paintings on the gadget then gadget constructive factors skill and so extra and consequently +VE If the gadget does paintings then it loses skill. So depreciation and consequently -VE yet another project. enable us to examine the formulation for the paintings performed W = F * s * cos @ Cos @ can anticipate +ve and -ve fee and so W turns into +ve or -ve. If @ is acute then W is +VE and if @ is obtuse then paintings is -ve This constructive and destructive sign stand as algegraical sign for the scalar quantity ie paintings, basically we've algebraical sign for electric fee that too is scalar. So information is something diverse yet those professionals have used the sign convention for some mathematical convenience to get the stairs easily. So we could continually supply their respective reaction to physics and chemistry instructors. permit me supply some education If the gasoline enclosed in a cylinder is assumed tochronic a wheel outdoors, then gasoline is the doer and wheel is the performed So paintings performed via the gasoline is +ve and paintings performed on the gasoline is -ve If we press the gasoline, then paintings performed on the gasoline would be +ve as we substitute into the doer.