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chemistry paper 1 stuff > paper 1 remembering stuff > Flashcards

paper 1 remembering stuff Flashcards

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1
Q

standard conditions for enthalpy

A

100kPa, 298K (25C), 1 mol^1dm^-3

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2
Q

standard enthalpy change of reaction

[don’t need to memorise]

A

the enthalpy change that accompanies a reaction in the molar quantities shown in a chemical equation under standard conditions, with all reactants and products in their standard state

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3
Q

enthalpy change of formation

[memorise]

A

the enthalpy change that takes place when one mole of a compound is formed from its elements under standard conditions, with all reactants and products in their standard state

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4
Q

enthalpy change of combustion

[memorise]

A

the enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions, with all reactants and products in their standard states

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5
Q

enthalpy change of neutralisation

[memorise]

A

the enthalpy change that accompanies the reaction of an acid by a base to form one mole of H2O(l) , under standard conditions, with all reactants and products in their standard states

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6
Q

[TESTS FOR ANIONS]

how do you test for a carbonate
gas based

A
  • add dilute nitric acid to solid/solution being tested
  • if you see bubbles, compound could be a carbonate
  • to prove gas is CO2 bubble gas through limewater

*carbonates react with acids to produce CO2

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7
Q

[TESTS FOR ANIONS]

how do you test for a sulfate
precipitate based

A
  • add barium nitrate
  • white precipitate should form

*most sulfates are soluble but BaSO4 is insoluble thus produces precipitate

**could also use barium chloride if not also testing for halide (as you are introducing Cl- ions to the solution)

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8
Q

[TESTS FOR ANIONS]

how do you test for a halide
precipitate based

A
  • add aqueous silver nitrate, AgNO3, to an aqueous solution of a halide
  • silver halide precipitates form
  • Add aqueous ammonia NH3(aq) to test solubility of precipitate
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9
Q

what are the results when testing halides (Cl-,Br- & I-)

A
  • Cl- AgCl=white. soluble in dilute NH3
  • Br- AgBr=cream. soluble in conc. NH3
  • I- AgI =yellow. insoluble in conc. NH3
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10
Q

what is the correct order for testing anions

A
  • carbonate, CO3^2- (only carbonates produce effervescent when reacting with acid)
  • sulfate, SO4^2- (2nd as BaCO3 is also a white precipitate and thus need to rule out CO3 first)
  • halides, Cl- Br- I- (both AgCO3 and AgSO4 are insoluble so need to rule out its not a carbonate or sulfate 1st)
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11
Q

how would you test a mixture of anions

A
  • carbonate test, add dilute nitric acid (HNO3) until bubbling stops so all CO3 has been reacted [xhCL, xh2SO4]
  • sulfate test, add excess Ba(NO3)2 and filter solution to remove barium sulfate [xBaCl2]
  • halide test, add AgNO3 (all sulfate and carbonate ions have already been removed). Add NH3 to test which halide
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12
Q

[TESTS FOR CATIONS]

how do you test for ammonium ions (NH4+)

A
  • add aqueous sodium hydroxide (NaOH)
  • ammonia gas is produced (no bubbles as its is soluble)
  • warm mixture & ammonia gas is released
  • test gas with moistures pH indicator paper, alkaline thus turn paper blue
  • NH4+ + OH- –> NH3 + H20
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13
Q

hydrogen bonding only happens with…

A

hydrogen + fluorine/ nitrogen/ oxygen

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14
Q

what is homogenous equilibrium

A

contains equilibrium species that are all in the same state or phase

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15
Q

what is heterogeneous equilibrium and how would you find its Kc

A

contains equilibrium constants in different states or phases. omit any solids or liquids from equation as they are constants. Kc only includes (g) or (aq)

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16
Q

how do you find the mole fraction for a gas eg. gas A

A

mole fraction x(A) = number of moles of A/ total number of moles in gas mixture

*the sum of all mole fractions in a gas mixture should = 1

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17
Q

how do you find the partial pressure for a gas eg. gas A

A 
p(A)= mole fraction A x total pressure P
p(A)= x(A) x P

*sum of partial pressure= total pressure

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18
Q

Kp only includes…

A

gasses as only gasses have partial pressure

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19
Q

when factor(s) change K (equilibrium constant)

A

ONLY TEMPERATURE

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20
Q

an alkali is…

A

a soluble base

21
Q

what is the Bronsted-Lowry definition of an acid

A

proton donor

22
Q

what is the Bronsted-Lowry definition of a base

A

proton acceptor

23
Q

hydronium ion

A

H3O+, water accepts a proton to form its conjugate acid can be used in place of an H+ in reactions

24
Q

how is a salt formed

A

a metal or ammonium ion replaces an H+ in an acid

25
Q

when writing ionic equations for reactions of acids

A

only the H+ and metal ion matter

26
Q

acid + metal

A

-> salt + hydrogen

27
Q

acid + carbonate

A

-> salt + CO2 + H2O

28
Q

acid + metal oxide

A

-> salt + water

29
Q

acid + alkali

A

-> salt + water

30
Q

log equation for pH

A

pH= -log[H+]

31
Q

log equation for [H+]

A

[H+]= 10^-pH

32
Q

pH increases in factors of …

A

10 ie. x10 between pH 3 & pH 4

33
Q

log equation for Ka

A

Ka = 10^-pKa

34
Q

log equation for pKa

A

pKa = -logKa

35
Q

the stronger the acid the … the Ka value and the … the pKa value

A

the stronger the acid the (greater) the Ka value and the (smaller) the pKa value

36
Q

the weaker the acid the … the Ka value and the … the pKa value

A

the weaker the acid the (smaller) the Ka value and the (bigger) the pKa value

37
Q

what are the 2 approximations made when finding the pH of a weak acid and when do they not work

A
  1. [H+] = [A-] as the dissociation of water is negligible. Unless very dilute or very weak acid is used
  2. the dissociation of a weak acid is so small you can use [HA] from start = [HA] at equilibrium rather than [HA] from start = [HA] at equilibrium - [H+] at eqm. unless [H+] is significant (ie. stronger acids)
38
Q

for weak acids what would the Ka expression look like

A

Ka = [H+]^2/[HA]

39
Q

equation for ionic product of water

A

Kw = [H+] x [OH-]

40
Q

how do you find the pH of a strong base

A

as base is strong [base]=[OH-], then use Kw expression to find [H+]

41
Q

in redox reactions where there is a missing reactant it is usually…

A

H2O

or H+/OH-

42
Q

what is standard electrode potential

A

the tendency to be reduced and gain electrons

43
Q

what are the conditions for a standard hydrogen electrode

A
  • 1 mol dm-3
  • 298K
  • 100kPa
44
Q

what is used when measuring a standard electrode potential

A
  • hydrogen half cell
  • salt bridge (allows ions to flow, contains electrolytes eg.KNO3)
  • wire (control flow of electrons)
45
Q

the more negative the electrode potential…

A

the greater the tendancy to lose electrons and undergo oxidation

46
Q

the more positive the electrode potential…

A

the greater the tendancy to gain electrons and undergo reduction

47
Q

standard cell potential =

A

+ve electrode - -ve electrode

48
Q

what is a buffer solution

A

a system that minimises pH changes when small amounts of an acid or base are added. Contain a weak acid and its conjugate base

chemistry paper 1 stuff (1 decks)

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