Definitions thermodynamics Flashcards

1
Q

Heat of reaction/reaction enthalapy

A

the enthalapy change accompanying the a chemical reaction at a certain temp and pressure

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2
Q

Std Reaction Enthalapy

A

the enthalapy change accompanying the conversion of 1 mol of reactant into product at stp(1 bar, 298K)

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3
Q

Enthalapy of formation. When is it std?

A

the enthalapy change accompanying the formation of 1 mol of a compound from it’s respective elements at their most stable state of aggregation at a certain temperature and pressure is called enthalapy of formation.

At 298K and 1 Bar, it is called std enthalaapy of formation

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4
Q

Enthalapy of combustion. When is it std?

A

It is defined as the enthalapy change accompanying the complete combustion of 1 mol of a compound in the presence of oxygen at a particular temperature and pressure.

It becomes std if p=1 bar and temp= 298K

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5
Q

Enthalapy of neutralisation. When is it std?

A

It is defined as the enthalapy change accompanying the complete neutralisation of 1 mol H+ ions from acid and OH- ions from base to form 1 mol of water at a particular temp and pressure is called the enthalapy of neutralisation.

it is std when p=1 bar and t= 298k

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6
Q

Enthalapy of dilution. When is it std? Infinite dilution?

A

The enthalapy change accompanying the addition of a given amount of solute to a given amount of solvent at a certain temp and pressure.

it is std when p=1 bar and t= 298K

Infinite dilution is amount of solvent»amount of solute

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7
Q

Enthalapy of fusion. When is it std?

A

The enthalapy change accompanying the conversion of 1 mol of solid into liquid at it’s melting point and certain pressure, is called enthalapy of fusion.

when p=1 bar, it is std enthalapy

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8
Q

Enthalapy of vaporization. When is it std?

A

The enthalapy change accompanying the conversion of 1 mol of liquid into gas at its boiling point and certain pressure.

p=1 bar

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9
Q

Enthalapy of sublimation. When is it std?

A

the enthalapy chnage accomapnying the coversion of 1 mol of solid into gas at sublimation point and certain pressure.

p=1 bar

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10
Q

Enthalapy of transformation

A

the enthalapy change accompanying the complete transformation of 1 mol of an allotrope of an element into another at transformation point and constant pressure.

p=1 bar

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11
Q

Hydration enthalapy

A

The anthalapy change in completely hydrating 1 mol of an anhydrous or a partially hydrated compound at particular temperature and pressure.

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12
Q

Lattice enthalapy

A

the enthalapy change accompanying formation of 1mol of an ionic compound from it’s constituent gaseous ions at a particular temp and pressure

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13
Q

Hess Law of Constant Heat Summation

A

If a reaction takes place in several steps then it’s standard reaction enthalapy is the sum of the the std enthalapies of the intermediate reactions into which the overall reactions can be divided at the same temperature.

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14
Q

Enthalapy of atomisation

A

enthalapy change accompanying the breaking of 1 mol of a particular type of bond to produce gaseous constituent atoms at a particular temp and pressure.

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15
Q

Spontaneity

A

A process that can take place on it’s own under given conditions once it has been initiated (if required).

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16
Q

Non-spontaneous/non-feasible

A

a process that requires continuous supply of external energy (or external aid) to be carried out

17
Q

Example of endothermic rxns that are spontaneous?

A

i) Melting of ice
ii) HgO(g) —heat—> Hg(l) + 1/2O2(g)
iii) 1/2N2 + O2 –> NO2(g)

18
Q

2nd Law of thermodynamics

A

for an isolated system, increase in entropy is the natural direction of a spontaneous process.
OR
the enthalapy of the universe is constantly increasing as it is as most of the processes are irreversible.