Thermodynamics- 1 Flashcards
What are the merits of thermodynamics
-> helps us to preducit whther a reaction will occur at a given set of conditions
- helps us to predict the extent of reaction,ie, how far the reaction will proceed, for reversible reactions
-> helps to deduce important laws such as, law of chemical equilibrium, distrubution laws
what are demerits of thermodynamics
-> It doesn’t give any information about the rate at whcih reaction occurs
-it only deals with the intial and final stages of a chemical reaction and gives no information about the mechanism of reaction
-> it only deals with bulk properites like pressure,temperature volume rather than individual particles like atoms and molecules.
what is system
the part of the universe under thermodynamic study
what is the surrounding
the remaining part of the universe excluding the system
the entire universe other than
the system is not affected by the changes
taking place in the system. Therefore, for
all practical purposes, the surroundings
are that portion of the remaining universe
which can interact with the system.
Usually, the region of space in the
neighbourhood of the system constitutes
its surroundings.
what is universe=
system+ surrounding= universe
what is boundary
The wall that separates
the system from the surroundings is called
boundary. This is designed to allow us to
control and keep track of all movements of
matter and energy in or out of the system(between system and surroundings).
This boundary may be real/imaginary.
what is
(i) open system
(ii) closed system
(iii) isolated system
(i) A system in which both matter and energy can be exchanged in between system and surrounding is called open system. Ex: animals, plants, water in an open vessel
(ii) A system that can exchange only energy between surroundings and sytem and no exhange of matter. Ex: water in a closed vessel.
The boundary of such systemis conducting.
(iii) There is no exchange of energy or open matter between system and surrounding. Ex: water in a thermos flask,
boundary wll be closed and insulating
what is the state of system
conditions of the system described in terms of measureable properties like pressure, temperature, volume etc. of system
what are state variables
We can describe the state of
a gas by quoting its pressure (p), volume (V),
temperature (T ), amount (n) etc. Variables like
p, V, T are called state variables or state
functions because their values depend only
on the state of the system(inital and final stages) and not on how it is
reached.
what is state function
State function is a phsyqical quantity whose value depends only on the state of the system and it does not depend upon the path by which the state has been attained.
EX: Pressure, Volume, Temperature, Free energy, entropy, enthalpy, internal energy
something is a state function because its value depends only upon final and initial states.
how many properties is needed to define a state
. In order to completely define the state
of a system it is not necessary to define all the
properties of the system; as only a certain
number of properties can be varied
independently. This number depends on the
nature of the system. Once these minimum
number of macroscopic properties are fixed,
others automatically have definite values.
what is macroscopic system?
A system which consists of a large number of chemical species such as atoms,molecules or ions is called as macroscopic system.
The properties of macroscopic system ( Ex: temperature, pressure, volume etc) are called macroscopic or thermodynamic propoerties,.
Differentiate between intensive and extensive propoerties
Intensive propoerties:
Properties that depend upon the nature of substance but are independent of the quantitiy/amount of substsance in a system.
Ex: specific heat capacity, specific volume, density,pressure, temperature, refractive index, emf of cell, molar heat capacity, freezing point/ mpt
extensive properties:
Properties that depend upon the quantity or amount or size of the substance in a system
Ex: Mass, Volume, heat capacity, Free energy, Internal energy, entropy, enthalpy
(m V C, GUSH)
can an extensive property become intensive? how? explain with examples
An extensive property can become intensive by specifying unit amount of the substance conerned.
For example, mass and volume are extensive properties but density and specific volume are intensive.
Density= mass/volume
specific volume= volume/mass
Heat capacity(C) is extensive property but specific heat capacity(c) and molar heat capacity(cₘ) is intensive.
an intensive property can be made by taking the ratio of 2 extensive properties.
what is thermodynamic equilibrium
A system is said to be in thermodynamic equilibrium if its macroscopic properties like temperature, pressure,volume etc do not change with time
