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A Level Chemistry > Oceans > Flashcards

Oceans Flashcards

1
Q

most ionic substances only dissolve in….

A

polar solvents

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2
Q

most covalent substances only dissolve in….

A

non-polar solvents

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3
Q

ionic solids dissolve in…
to make….

A

water
aqueous solutions

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4
Q

standard lattice enthalpy is….

A

the enthalpy change when 1 mol of an ionic lattice is formed from its gaseous ions under standard conditions

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5
Q

lattice enthalpy is always….
because….

A

negative
bonds are being broken and energy is being released

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6
Q

the more negative the lattice enthalpy….

A

the stronger the bonding

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7
Q

enthalpy change of hydration ions is…

A

the enthalpy change when 1 mol of aqueous ions is formed from gaseous ions

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8
Q

the enthalpy change of solution is….

A

the enthalpy change when 1 mol of an ionic substance dissolves enough to form an indefinitely dilute solution

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9
Q

you can use a _______ _____ or _____ _____ _____ to find the enthalpy change of solution

A

enthalpy cycle
enthalpy level diagram

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10
Q

charge density of an ion =

A

charge / radius

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11
Q

ions with higher charge density have more exothermic lattice enthalpy, why?

A

the ions are better at attracting each other so ionic bonds are stronger. meaning more energy is released when bonds are made

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12
Q

ions with higher charge density have more exothermic hydration enthalpy, why?

A

ions are better at attracting water molecules so the intermolecular bonds are stronger. meaning more energy is released when bonds are made

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13
Q

entropy, S, is…

A

a measure of the number of ways that particles can be arranged and the number of ways the energy can be shared out between particles

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14
Q

how does physical state affect entropy?

A

solids - hardly any disorder
liquids - some disorder
gases - most disordered

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15
Q

which physical state has the highest entropy?

A

gas

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16
Q

which physical state has the lowest entropy?

A

solid

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17
Q

how does no. of moles affect entropy?

A

when no. of moles increases, entropy increases

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18
Q

ΔtotS =

A

ΔsysS + ΔsurrS

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19
Q

ΔsysS =

A

S products - S reactants

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20
Q

ΔsurrS =

A

-enthalpy change / T (k)

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21
Q

a feasible reaction is….

A

one that once started will carry on to completion without zero energy being supplied to it

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22
Q

for a reaction to be feasible the total entropy change must be…

A

positive or zero

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23
Q

the equation for finding the temperature for a feasible reaction to occur is…

A

T = ΔH / ΔsysS

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24
Q

Ksp is….

A

the solubility product

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25
Q

when a sparingly soluble solid is dissolved in water to give a saturated solution…

A

an equilibrium is established

26
Q

for the reaction
AaBb (s) –> aA^b+ (aq) + bB^a- (aq)
write the expression for Ksp

A

(A^b+(aq))^a + (B^a-(aq))^b

27
Q

for the reaction
AB (s) —> A+ (aq) + B- (aq)
write the equation for Ksp

A

Ksp = (solubility of AB)^2

28
Q

a neutral solution is one where…

A

H+ conc = OH- conc

29
Q

pH =

A

-log10 [H+]

30
Q

strong acids are..

A

monoprotic

31
Q

monoprotic means…..

A

each mole of acid produces one mole of hydrogen ions

32
Q

[H+] =

A

10 ^-pH

33
Q

water can act as…

A

a base and an acid

34
Q

Kw is…
and is only used for finding the…

A

the ionic product of water
pH of strong acids

35
Q

Kw =

A

[H+] [OH-]

36
Q

Ka is..
and is only used for…

A

acid dissociation constant
weak acids

37
Q

Ka =

A

[H+]^2 / [HA]

38
Q

pKa =

A

-log10 Ka

39
Q

a buffer is..

A

a solution that resists changes in pH when a small amount of acid or base are added or it’s diluted

40
Q

acidic buffers are made by..

A

mixing a weak acid with one of its salts

41
Q

in acidic buffers the weak acid…
and the salt..

A

slightly dissociates
completely dissociates

42
Q

if you increase the conc of acid in the buffer

A

the [H+] conc increases shifting equilibrium to the LHS and pH doesn’t change

43
Q

if you increases the conc of the base in the buffer

A

the [OH-] conc increases shifting eqm to the RHS and pH doesnt change

44
Q

the types of radiation that reaches the Earth’s surface are

A

visible light and UV

45
Q

the type of radiation that the Earth emits is

A

infrared radiation (heat)

46
Q

the ‘IR’ window is…

A

the range of IR frequencies that are not absorbed by atmospheric gases so escapes into space

47
Q

the main greenhouse gases are…

A

water vapour
methane
CO2

48
Q

greenhouse gases absorb ________ to make bonds in the molecule _____ more. this extra vibrational energy is _________ on to other molecules in the air by ________ , giving the other molecules more kinetic energy so raising the overall ________

A

IR radiation
vibrate
passed
collisions
temperature

49
Q

a bronsted lowry acid is a….

A

proton donator

50
Q

a weak acid is…

A

one that partially dissociates

51
Q

For the ion H2PO4-
state the conjugate base

A

HPO4^2-

52
Q

For the ion H2PO4-
state the conjugate acid

A

H3PO4^-

53
Q

what factors determine the pH of a buffer solution?

A
  • Ka
  • temperature
54
Q

what is meant by the term conjugate acid-base pairs?

A

two species differing in H+

55
Q

in water strong acids..

A

dissociate completely

56
Q

in water strong bases…

A

ionise completely

57
Q

a Bronsted Lowry base is a…

A

proton acceptor

58
Q

in water weak acids….

A

only dissociate slightly

59
Q

what is transferred when acids and bases react?

A

protons

60
Q

for strong monoprotic acids [H+] =

A

[acid]

61
Q

if given the pH of a solution you can calculate the [H+]

A

10^-pH

62
Q

what is the pH of a strong base at 298k given by?

A

pH = 14 + log[OH-]

A Level Chemistry (12 decks)

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