First law of thermodynamics

First law of thermodynamics

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  Bangabandhu Sheikh MujiburRahman Science and Technology University A presentation on first law of thermodynamics Presented by Md. Shimul Bhuia St. ID: 16PHR003 Department of Pharmacy
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  Thermodynamics • Thermodynamics isa branch of physics concerned with heat and temperature and their relation to energy and work .In particular, it describes how thermal energy is converted to and from other forms of energy and how it affects matter.
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  The first lawof thermodynamics • The first law of thermodynamics states that the amount of heat given to a system is equal to the sum increase in the internal energy of the system and the external work done.
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  Thermodynamics systems • Athermodynamic system is the material and radiative content of a macroscopic volume in space, that can be adequately described by thermodynamic state variables such as temperature, entropy, internal energy and pressure
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  Statement of thefirst law of thermodynamics • Conservation of energy • Energy can neither be created nor destroyed but it can change forms • Total amount of energy in a closed system remains constant
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  Description with formula •Heat/work formula: ΔU=Q-W • dU= Δ Q-PdV [W=PdV]
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  Significance • The totalamount of energy in the world is constant. • It is impossible to get more energy oyt of a system than is put into it. • You can’t get energy from nothing.
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  Application • Can beused to find the latent heat of vaporization • It is used to calculate the quantity to raise the temperature of an ideal gas
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  Limitation of firstlaw Limitation:- First law does not help to predict whether the certain process is possible or not. Reason:- It does not specify that heat cannot flow from low temperature body to a high temperature body Limitation:-The first law does not give information about direction. Reason :For example it puts no restriction on the direction of the flow of heat, whether heat can flow from a cold body to a hot body or vice versa.
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  Conclusion • The 1stlaw of thermodynamics simply says that the amount energy in a closed system remains constant. • Regardless of how it is changed or is moved around. • To add energy to a system it needs to come from some place else