Enthalpy, entropy, free energy Flashcards

1
Q

ΔLEH⦵

A

enthaply change when 1 mole of a solid ionic compound is formed from its gaseous ions

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2
Q

ΔfH⦵

A

enthalpy change when 1 mole of a compound is formed from its elements

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3
Q

ΔatH⦵ (element)

A

enthalpy change when 1 mole of gaseous atoms is formed from an element

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4
Q

ΔatH⦵ (compound)

A

enthalpy change when 1 mole of a compound is converted to gaseous atoms

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5
Q

ΔhydH⦵

A

enthalpy change when 1 moles of gaseous ions is dissolved in water

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6
Q

ΔsolH⦵

A

enthalpy change when 1 mole of solute is dissolved in a solvent, such as water

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7
Q

is ΔatH⦵ always endo or exothermic

A

endothermic, as bonds must be broken for it to happen

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8
Q

What are standard conditions

A

100kPa (1atm) 298K (25°C)

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9
Q

are first/second ionisation energies always endo or exothermic

A

endothermic, must overcome the attraction between electrons and nucleus

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10
Q

is first electron affinity endo or exothermic

A

exothermic

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11
Q

is second electron affinity endo or exothermic

A

endothermic

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12
Q

what are the 2 factors that affect lattice enthalpy

A

-ionic charge -ionic radius

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13
Q

how does ionic charge effect lattice enthalpy

A

higher charges on ions -> stronger electrostatic attraction between ion -> more energy released when lattice forms -> more negative enthalpies

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14
Q

how does ionic radius effect lattice enthalpy

A

smaller ionic radii of ions formed, higher the charge density of the ion. greater electrostatic attraction between ions, so lattice more exothermic.

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15
Q

how do you calculate ΔsolH⦵

A

-ΔLEH + ΣΔhydH

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16
Q

draw an enthalpy cycle for calculating the enthalpy change of solution

A
17
Q

how do you calculate entropy change (ΔS)

A

ΔS = Sproducts - Sreactants

18
Q

how do you calculate free energy change (ΔG)

A

ΔG = ΔH - TΔS

19
Q

how do you calculate the temp at which a reaction becomes feasible

A

ΔT = ΔH/ΔS

20
Q

is a reaction with a negative ΔH but positive ΔS feasible/ maybe feasible or never

A

always feasible

21
Q

is a reaction with a positive ΔH and positive ΔS feasible/ maybe feasible or never

A

maybe, only above certain temp

22
Q

is a reaction with a negative ΔH but negative ΔS feasible/ maybe feasible or never

A

maybe, only below certain temp

23
Q

is a reaction with a positive ΔH but negative ΔS feasible/ maybe feasible or never

A

never feasible

24
Q

draw an enthalpy cycle for calculating the enthalpy change of solution

A
25
Q

define average bond enthalpy

A

energy need to break 1 mole of a bond in the gas phase, average over the different compounds that the bond is found in.