Fichas
Chapter 17: Aqueous Ionic Equilibrium

Fichas del conjunto (106)
- 1buffers- solutions that resist pH change
- contains weak acid and conjugate base or weak base and conjugate acid
weak acid = HNO₂ weak base = NaNO₂ - 2solubility equilibriaextent to which slightly soluble ionic compounds dissolve in water
- 3weak acid or base by itself doesn't contain sufficient _____ or _____ to be a bufferbase
acid - 4to determine the pH of a buffer solution containing common ions, the initial [] should include the _____ and its _____ _____acid
conjugate base - 5calculate the pH of a buffer that is 0.200 M in HC₂H₃O₂ and 0.100 M in NaC₂H₃O₂. HC₂H₃O₂ Kₐ = 1.8 × 10⁻⁵ step 1: write the balanced equation for ionization of the acidstep 1: write the balanced equation for ionization of the acid
HC₂H₃O₂ + H2O ⇆ H₃O⁺ + C₂H₃O₂⁻ - 6calculate the pH of a buffer that is 0.200 M in HC₂H₃O₂ and 0.100 M in NaC₂H₃O₂. HC₂H₃O₂ Kₐ = 1.8 × 10⁻⁵ step 2: Use Ice for weak acid solutions

- 7to determine [H₃O⁺] for any buffer solution, multiply Kₐ by the ratio of the [] of the _____ and _____ _____acid
conjugate base
[H₃O⁺] = Kₐ × ([HA]/[A⁻]) - 8log AB = log A + log B then -log AB =-log A - log B
- 9in any solution where acid/conjugate base [] are = then [H₃O⁺] = _____ and the pH of the buffer is = _____Kₐ
pKₐ - 10Henderson-Hasselbalch equationallows us to quickly calculate the pH of a buffer solution from the initial [] of the buffer components (as long as x is small approximation)
- 11Henderson-Hasselbalch equation formulaEnter text here...

- 12If the pH of the buffer is < than pKₐ of the acid, then the buffer must contain _____ acid than the basemore
- 13what happens when you add acid to a buffer-added acid is neutralized
- neutralizing H⁺ uses base A⁻ creating HA
conjugate acid: H⁺ + A⁻ → HA
- decreases pH of buffer - 14what happens when you add base to a buffer-added base is neutralized
- neutralizing OH⁻ uses conjugate acid HA creating base A⁻: OH⁻ + HA → H₂O + A⁻
- increases the pH of the buffer - 15what happens when you add base to a buffer (visual)Enter text here...

- 16calculating pH change in a buffer solution after adding small amt of acid/base: step 1 buffer has: HC₂H₃O₂: 0.100 mol NaC₂H₃O₂: 0.100 mol & Kₐ 1.8 × 10⁻⁵ NaOH: 0.015 mol added find pHstep 1: calculate initial []

- 17calculating pH change in a buffer solution after adding small amt of acid/base: step 1 explain- Eq 4 addition of NaOH to buffer
- 1st row: init [] of acid & base
- 2nd row: [NaOH] added, [NaOH] subtracted from [acid] and + to [base]
- NaOH used to ionize acid/create base
- 3rd row: new [acid], [base] & [NaOH]. [] used 4 ICE where remaining [acid] ionizes w/water - 18calculating pH change in a buffer solution after adding small amt of acid/base: step 2 buffer has: HC₂H₃O₂: 0.100 mol NaC₂H₃O₂: 0.100 mol & Kₐ 1.8 × 10⁻⁵ NaOH: 0.015 mol added find pHEnter text here...

- 19calculating pH change in a buffer solution after adding small amt of acid/base: step 2 explain- Eq 4 remaining [acid] from step 1 as it ionizes w/water
- 1st row: init [] of acid from step 1
- 2nd row: unknown [acid] ionized (weak)
- 3rd row: new [acid] after ionization
- Ka used to determin [H₃O⁺] and pH - 20calculating pH change in a buffer solution after adding small amt of acid/base: Henderson-Hasselbalch equation buffer has: HC₂H₃O₂: 0.100 mol NaC₂H₃O₂: 0.100 mol & Kₐ 1.8 × 10⁻⁵ NaOH: 0.015 mol added find pHUse ICE to get final [acid] and [base] in moles

- 21when calculating change in buffers containing a base and its conjugate acid, calculate pKₐ for the _____ acid of the _____ baseconjugate
weak - 22pKₐ + pKᵇ =14
- 23calculate pH change 4 buffer solution of a base w/conjugate acid, after adding small amt of acid/base: step 1 buffer has: NH₃ = 0.50 M NH4Cl = 0.20 M & Kᵇ = 4.75 HCl: 30 ml added find pHstep 1: find pKₐ
pKₐ + pKᵇ = 14
pKₐ = 14 - 4.75
pKₐ = 9.65 - 24calculate pH change 4 buffer solution of a base w/conjugate acid, after adding small amt of acid/base: step 2 buffer has: NH₃ = 0.50 M NH4Cl = 0.20 M & Kᵇ = 4.75 HCl: 30 ml added find pHstep 2: get moles of added substance
(1 M HCl / 1L) × (.300 L) = .03 M of HCl - 25calculate pH change 4 buffer solution of a base w/conjugate acid, after adding small amt of acid/base: step 3 buffer has: NH₃ = 0.50 M NH₄Cl = 0.20 M & Kᵇ = 4.75 HCl: 30 ml added find pH

- 26an effective buffer neutralizes ______ to _____ amounts of added acid or basesmall
moderate - 27factors that influence effectiveness of a buffer- relative amts of acid and conjugate base
- absolute [] of the acid and conjugate base - 28capacity of bufferhow much added acid or base it can effectively neutralize
- 29range of bufferthe pH range over which a particular acid and its conjugate base can be effective
- 30a buffer is most effective when the [] of acid and conjugate base are _____equal
- 31a buffer is least effective as the difference in the amts of acid and conjugate base _____increase
- 32guideline: effective buffer must have a [base]/[acid] ratio in the range of _____ to _____. [] of base/acid shouldn't differ by more than a factor of0.1
10
10 - 33a buffer is most effective whent [] of acid and conjugate base are _____high
- 34the more _____ the buffer components, the less effective the buffedilute
- 35the effective range for a buffering system is one pH unit on either side of _____pKₐ
- 36a weak acid has a pKₐ of 5.0. what is its effective range?pH range of 4.0 - 6.0
- 37Preparing a buffer example: which would you mix w/sodium salt to make a buffer w/pH of 4.25? HCHO₂ w/pKₐ = 3.74 or HNO₂ w/pKₐ = 3.34pH = pKₐ + log (base/acid)
4.25 = 3.74 + log(base/acid)
0.51 = log(base/acid)
10^0.51 = log(base/acid)
3.24 - 38buffer capacity- amt of acid/base that can be added to a buffer w/out causing a large change in pH
- 39buffer capacity _____ w/increasing absolute concentrations of the buffer componentsincreases
- 40buffer capacity _____ increases as the relative [] of the buffer components become _____ to each otherincreases
similar - 41as the ratio of the buffer components get closer to _____, the overall capacity of the buffer becomes _____one
greater - 42acid-base titration- basic/acidic solution of unknown [] reacts w/acidic/basic solution of known []
- known solution slowly added to unknown
- pH monitored
- acid/base mix & neutralize each other
- ends at equivalence point - 43equivalence point- when # of mole of base = # of moles of acid initially in solution
- 44titration curve or pH curvea plot of the pH of the solution during a titration
- 45pH changes _____ near the equivalence point. small amts of added base cause _____ changes in pHquickly
large - 46Strong Acid w/Strong Base Titration 20.0 mL of 0.125 M HNO3 w/ 0.150 M NaOH step 1: get initial pH before adding basestrong acid [H₃O+] = M
pH = -log(0.125) = 0.90 - 47Strong Acid w/Strong Base Titration 20.0 mL of 0.125 M HNO3 w/ 0.150 M NaOH step 2: get volume of base needed to reach equivalence

- 48Strong Acid w/Strong Base Titration 20.0 mL of 0.125 M HNO3 w/ 0.150 M NaOH step 3: add 5 mL of base - get moles

- 49Strong Acid w/Strong Base Titration 20.0 mL of 0.125 M HNO3 w/ 0.150 M NaOH step 4: add 5mL of base - get final []
![Strong Acid w/Strong Base Titration 20.0 mL of 0.125 M HNO3 w/ 0.150 M NaOH step 4: add 5mL of base - get final []](https://examtimeassets.s3.amazonaws.com/uploads/media/image/21535019/desktop_07f66ee1-8ba6-46b7-920b-6a4d9ccb6e23.png)
- 50Strong Acid w/Strong Base Titration 20.0 mL of 0.125 M HNO3 w/ 0.150 M NaOH step 5: add 5mL of base - get [H₃O⁺]- [H₃O⁺] = (H₃O⁺ moles / ttl volume)
[H₃O⁺] = (1.75 × 10⁻³) / (0.020 L + 0.005L)
[H₃O⁺] = 7 × 10⁻²
0.020 L = initial volume
0.005L = added base volume - 51Strong Acid w/Strong Base Titration 20.0 mL of 0.125 M HNO3 w/ 0.150 M NaOH step 6: add 5mL of base - pHpH = -log [H₃O⁺]
pH = -log (7 × 10⁻²)
pH = 1.15 - 52Strong Acid w/Strong Base Titration 20.0 mL of 0.125 M HNO3 w/ 0.150 M NaOH step 7: add ttl of 0.167 L of base (volume for equivalence) get pH @ equivalence point- pH 7
- strong base has completely neutralized the strong acid
- only source of H₃O+ is the ionization of water - 53Strong Acid w/Strong Base Titration 20.0 mL of 0.125 M HNO3 w/ 0.150 M NaOH step 8: add 5 mL past equivalence point (0.0217 L) and get OH⁻ moles addedpast equivalence point there is
[OH⁻] > [H₃O⁺]
moles OH⁻ added =
0.0217 L × 0.150 M NaOH = 0.0033 - 54Strong Acid w/Strong Base Titration 20.0 mL of 0.125 M HNO3 w/ 0.150 M NaOH step 9: add 5 mL past equivalence point (0.0217 L) and get OH⁻ moles left overOH⁻ moles left over = OH⁻ added - init H₃O⁺
0.000755 = 0.0033 - .0025 - 55Strong Acid w/Strong Base Titration 20.0 mL of 0.125 M HNO3 w/ 0.150 M NaOH step 10: add 5 mL past equivalence point (0.0217 L) and get [OH⁻][OH⁻] = 0.000755 / (0.020 L + 0.0217L)
[OH⁻] = 0.018
0.020 L = initial volume
0.0217L = added base volume - 56Strong Acid w/Strong Base Titration 20.0 mL of 0.125 M HNO3 w/ 0.150 M NaOH step 11: add 5 mL past equivalence point (0.0217 L) and get pHpOH = -log([OH⁻])
pOH = -log(0.018)
pOH = 1.74
pH = 14 - 1.74 = 12.26 - 57Strong Acid w/Strong Base Titration graph

- 58Strong Acid w/Strong Base Titration The initial pH is the pH of the strong _____ solutionacid
- 59Strong Acid w/Strong Base Titration B4 equivalence point, _____ is in excess. Calculate it by subtracting the # of moles of added _____ from the initial # of moles of _____ and dividing by _____ _____.H₃O⁺
OH⁻
H₃O⁺
total volume - 60Strong Acid w/Strong Base Titration @ equivalence point pH =7
- 61Strong Acid w/Strong Base Titration Beyond equivalence point, _____ is in excess. Calculate it by subtracting the # of moles of added _____ from the initial # of moles of _____ and dividing by _____ _____.OH⁻
H₃O⁺
OH⁻
total volume - 62Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 1: get initial pH before adding base

- 63Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 2: get volume of base needed to reach equivalence

- 64Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 3: add 5 mL of base - get moles

- 65Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 4: add 5mL of base - get [] and pH
![Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 4: add 5mL of base - get [] and pH](https://examtimeassets.s3.amazonaws.com/uploads/media/image/21534205/desktop_6e7a4850-2d8c-4e9f-97cd-ea715c8f3f7e.png)
- 66Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 4: details- after adding the base, the solution contains significant amounts of both an acid and its conjugate base
- the solution is now a buffer - 67Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 5: get pH @ 1/2 of equivalence point- amt of added base = 1/2 init [acid]:
NaOH = 1.05 x 10⁻³ moles
- 1/2 of init amt of acid has been converted to its conjugate base
- results in [base] = [acid]
- for any buffer where weak acids = conjugate acid, then pH = pKₐ = 4.74 - 68Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 6: get [ion] to get pH @ equivalence point
![Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 6: get [ion] to get pH @ equivalence point](https://examtimeassets.s3.amazonaws.com/uploads/media/image/21536010/desktop_9482361d-42d7-42d1-9ee9-b554bf889b5a.png)
- 69Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 6: details- base has ionized all [CH₃COOH]
- only thing left is [CH₃COO⁻] → weak base
- the solution is no longer a buffer
- must calculate the init [CH₃COO⁻] to get pH - 70Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 7: get Kᵇ to get pH @ equivalence point

- 71Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 8: get pH @ equivalence point

- 72Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 8: details- pH at the equivalence point is not neutral but basic
- all acid has been converted into its conjugate base, resulting in a weakly basic solution - 73Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 9: get [OH⁻] 5mL after equivalence point[OH⁻] = 6.25 × 10⁻⁴ / (0.020 L + 0.0218L)
[OH⁻] = 0.0149 M
6.25 × 10⁻⁴ = amt of OH remaining
0.020 L = initial volume
0.0218L = added base volume
- solution mix of strong base / weak base
- strong base overwhelms weak base
- calculate pH by strong base - 74Weak Acid w/Strong Base Titration 20.0 mL of 0.105 M CH₃COOH (Kₐ 1.8x10⁻⁵) w/ 0.125 M NaOH step 10: get pH 5 mL after equivalence pointpOH = -log [OH⁻]
pOH = -log (0.0149) = 1.83
pH = 14 - 1.83 = 12.17 - 75Weak Acid w/Strong Base Titration graph

- 76Weak Acid w/Strong Base Titration initial pH is that of the _____ acid solutionweak
- 77Weak Acid w/Strong Base Titration between the init pH and equivalence point, the solution becomes a ____buffer
- 78Weak Acid w/Strong Base Titration 1/2 way to the equivalence point, the buffer components are _____ and pH =equal
pKa - 79Weak Acid w/Strong Base Titration @ equivalence point, the acid has _____ been converted into its _____ _____all
conjugated base - 80Weak Acid w/Strong Base Titration calculate the [] of ion acting as weak base by dividing the # of _____ of _____ by the ttl _____ @ the equivalence pointmoles
ion
volume - 81Weak Acid w/Strong Base Titration beyond the equivalence point _____ is in excess. ignore the weak base and calculate the _____ by subtracting init # of moles of the ____ acid from the # of moles of added _____ and dividing by the _____ _____OH⁻
[OH⁻]
weak
OH⁻
total volume - 82can monitor pH of a titration w/ a _____ _____ or an _____. With an indicator, the _____ is when it changes color and determines the _____ _____.pH meter
indicator
endpoint
equivalence point - 83solubility-product constant Kₛₚ- equilibrium constant for a chemical equation representing the dissolution of an ionic compound
- has only 1 value at a given temp - 84solubility of a compound is- the quantity of the compound that dissolves in a certain amount of liquid
- can have different values in different kinds of solutions - 85molar solubilitythe solubility in units of moles per liter mol/L
- 86Kₛₚ formula

- 87relationship between Kₛₚ and molar solubility depends on the _____ of the dissociation reaction. can only compare Kₛₚ values for different compounds if the compounds have the same dissociation _____.stoichiometry; stoichiometry
i.e. Mg(OH)₂ and CaF₂
both have same stoichiometry; 1 mol of each produces 3 mol of dissolved ions - 88solubility of an ionic compound is _____ in a solution containing a common ion than in pure water. equilibrium shifts to the _____. solubility is _____.lower
left
decreased - 89calculate the molar solubility in the presence of a common ion: step 1 what's the molar solubility of CaF₂ in a solution containing 0.100 M NaFstep 1: write reaction eq & ksp eq
CaF₂ ⇄ Ca²⁺ + 2F⁻
Kₛₚ = [Ca²⁺] [F⁻]² - 90calculate the molar solubility in the presence of a common ion: step 2 what's the molar solubility of CaF₂ in a solution containing 0.100 M NaF

- 91solubility of an ionic compound w/a strong or weak basic anion _____ with increasing acidity (decreasing pH)increases
BaF₂: soluble in acidic solution because F₂ is a base
AgI: not solubility not greater in acidic soltuion, I- is not a base - 92Q (reaction quotient) and Kₛₚ- Kₛₚ value of product @ equilibrium
- Q follows same format as Kₛₚ
- Q value of product under any conditions
- Q used to compare solution w/differnt [] to a solution @ equilibrium - 93Q < Kₛₚ- reaction proceeds to right, to product
- unsaturated solution - 94Q = Kₛₚ- reaction @ equilibrium
- saturated solution - 95Q > Kₛₚ- reaction proceeds to left, to reactants
- solid normally precipitates
- unsaturated solution
- sometimes Q can remain greater than K → supersaturated solution: unstable and forms a precipitate when disturbed - 96Predicting Precipitation Reactions 0.0150M of Pb(NO₃) and 0.00350 NaBr are mixed. Does a precipitate form? step 1-list possible products & their solubility
- soluble products won't precipitate
NaNO₃ = soluble
PbBr₂: Kₛₚ = 4.67 × 10⁻⁶ - 97Predicting Precipitation Reactions 0.0150M of Pb(NO₃) and 0.00350 NaBr are mixed. Does a precipitate form? step 2- Calculate Q and compare to Kₛₚ for product w/Ksp from step 1
PbBr₂: Kₛₚ = 4.67 × 10⁻⁶
Q = [Pb²⁺][Br⁻]²
Q = (0.0150)(0.00350)² = 1.84 × 10⁻⁷
Q < K = precipitate forms - 98A solution may contain several different dissolved metal cations that can be separated by selective precipitation. What is selective precipitation?A process involving the addition of a reagent that forms a precipitate w/one of the dissolved cations but not the others
- 99for selective precipitation to work, Kₛₚ value must differ by at least a factor of _____10³
- 100Finding min required reagent [] for selective precipitation [Mg²⁺] = 0.059 M, [Ca²⁺] = 0.11M can be seperated by KOH. Kₛₚ = 2.06 × 10⁻¹³ What min [OH⁻] triggers precipitationprecipitation begins when Q = Kₛₚ; this is [] above which compound precipitates
Q = [Mg²⁺][OH⁻]²
2.06 × 10⁻¹³ = (0.059)[OH⁻]²
1.9 × 10⁻⁶ = [OH⁻] - 101Finding [] ions left after selective precipitation: step 1 [Mg²⁺] = 0.059 M w/Kₛₚ = 2.06 × 10⁻¹³, [Ca²⁺] = 0.11M w/Kₛₚ = 4.68 × 10⁻⁶ can be seperated by KOH. What is [Mg²⁺] when Ca²⁺ begins to precipitate.step 1: get [OH⁻] when Ca²⁺ begins to precipitate
Q = [Ca²⁺][OH⁻]²
2.06 × 10⁻¹³ = (0.011)[OH⁻]²
2.06 × 10⁻² = [OH⁻] - 102Finding [] ions left after selective precipitation: step 2 [Mg²⁺] = 0.059 M w/Kₛₚ = 2.06 × 10⁻¹³, [Ca²⁺] = 0.11M w/Kₛₚ = 4.68 × 10⁻⁶ can be seperated by KOH. What is [Mg²⁺] when Ca²⁺ begins to precipitate.step 1: get [Mg²⁺] that remains when Ca(OH)₂ begins 2 precipitate.
use [OH⁻] / Q = values from step 1
Q = [Mg²⁺][OH⁻]²
2.06 × 10⁻¹³ = [Mg²⁺][2.06 × 10⁻²]²
4.9 × 10⁻¹⁰ = [Mg²⁺] - 103a solution of _____ [acid] shows a higher value of Ka compared to a _____ [acid]less
more - 104ph = pKa then[base] = [acid]
ph = 7 - 105ph > pKa then[base] > [acid]
ph > 7 - 106ph < pKa then[base] < [acid]
ph < 7
Información
- Descripción
- (Chem II) General Chemistry Fichas sobre Chapter 17: Aqueous Ionic Equilibrium, creado por Alexandra Bozan el 29/07/2019.
- Creado por
- Alexandra Bozan
- Visitas
- 1
- Valoración