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Questions and Answers
When aqueous solutions of $AgNO_3$ and $NaCl$ are mixed, what is the net ionic equation?
When aqueous solutions of $AgNO_3$ and $NaCl$ are mixed, what is the net ionic equation?
- $Na^+ (aq) + Cl^- (aq) \rightarrow NaCl (s)$
- $Na^+ (aq) + NO_3^- (aq) \rightarrow NaNO_3 (aq)$
- $Ag^+ (aq) + NO_3^- (aq) \rightarrow AgNO_3 (s)$
- $Ag^+ (aq) + Cl^- (aq) \rightarrow AgCl (s)$ (correct)
When $Ca(NO_3)_2$ and $K_2CO_3$ solutions are mixed, which compound precipitates?
When $Ca(NO_3)_2$ and $K_2CO_3$ solutions are mixed, which compound precipitates?
- Potassium carbonate
- Calcium carbonate (correct)
- Calcium nitrate
- Potassium nitrate
Which of the following compounds is most soluble given their $K_{sp}$ values: $CaCO_3 (K_{sp} = 1.0 \times 10^{-10})$, $Mg(OH)2 (K{sp} = 1.2 \times 10^{-11})$, $Al(OH)3 (K{sp} = 3.3 \times 10^{-33})$, $PbS (K_{sp} = 3.0 \times 10^{-28})$?
Which of the following compounds is most soluble given their $K_{sp}$ values: $CaCO_3 (K_{sp} = 1.0 \times 10^{-10})$, $Mg(OH)2 (K{sp} = 1.2 \times 10^{-11})$, $Al(OH)3 (K{sp} = 3.3 \times 10^{-33})$, $PbS (K_{sp} = 3.0 \times 10^{-28})$?
- $Al(OH)_3$
- $Mg(OH)_2$ (correct)
- $PbS$
- $CaCO_3$
What is the molar solubility of $Ag_2CO_3$ (Ksp = $4 \times 10^{-12}$)?
What is the molar solubility of $Ag_2CO_3$ (Ksp = $4 \times 10^{-12}$)?
The $K_{sp}$ of $Cd_3(PO_4)_2$ at $18^\circ C$ is $1.08 \times 10^{-33}$. What is its molar solubility at this temperature?
The $K_{sp}$ of $Cd_3(PO_4)_2$ at $18^\circ C$ is $1.08 \times 10^{-33}$. What is its molar solubility at this temperature?
What is the molar solubility of $Mg^{2+}$ in a saturated solution of $Mg(OH)2$ after adding 0.1 M NaOH, given that the $K{sp}$ for $Mg(OH)_2$ is $1.2 \times 10^{-11}$?
What is the molar solubility of $Mg^{2+}$ in a saturated solution of $Mg(OH)2$ after adding 0.1 M NaOH, given that the $K{sp}$ for $Mg(OH)_2$ is $1.2 \times 10^{-11}$?
A solution contains 1 M $Ag^+$ and 0.1 M $Pb^{2+}$. If $NaCl$ is added, which cation precipitates first and by how many magnitudes, given $K_{sp}(AgCl) = 10^{-10}$ and $K_{sp}(PbCl_2) = 10^{-5}$?
A solution contains 1 M $Ag^+$ and 0.1 M $Pb^{2+}$. If $NaCl$ is added, which cation precipitates first and by how many magnitudes, given $K_{sp}(AgCl) = 10^{-10}$ and $K_{sp}(PbCl_2) = 10^{-5}$?
Which substance is incorrectly identified as a type of acid or base?
Which substance is incorrectly identified as a type of acid or base?
Which statement about $K_w$ is always true?
Which statement about $K_w$ is always true?
What is the pOH of a solution with a proton concentration of $10^{-4} M$?
What is the pOH of a solution with a proton concentration of $10^{-4} M$?
If the $K_b$ for ammonia is $10^{-4}$, what is the $pK_a$ for its conjugate acid?
If the $K_b$ for ammonia is $10^{-4}$, what is the $pK_a$ for its conjugate acid?
Given these acids in order of decreasing strength ($HCl, H_3O^+, HCN$), what is the order of decreasing base strength of their conjugate bases?
Given these acids in order of decreasing strength ($HCl, H_3O^+, HCN$), what is the order of decreasing base strength of their conjugate bases?
What is the pH of $10^{-2.5} M$ nitric acid?
What is the pH of $10^{-2.5} M$ nitric acid?
What is the pH of a 0.1 M $CH_3NH_3Cl$ solution, given the $K_b$ for $CH_3NH_2$ is $10^{-5}$?
What is the pH of a 0.1 M $CH_3NH_3Cl$ solution, given the $K_b$ for $CH_3NH_2$ is $10^{-5}$?
The ratio of $NH_3$ to $NH_4Br$ in an aqueous solution is 4. If the $NH_3$ concentration is $3.2 \times 10^{-3}$ and its $K_b$ is $10^{-5}$, what is the pH?
The ratio of $NH_3$ to $NH_4Br$ in an aqueous solution is 4. If the $NH_3$ concentration is $3.2 \times 10^{-3}$ and its $K_b$ is $10^{-5}$, what is the pH?
If 100 mL of 1 M $HClO_4$ is titrated with 900 mL of 0.1 M $NaOH$, what is the resulting pH?
If 100 mL of 1 M $HClO_4$ is titrated with 900 mL of 0.1 M $NaOH$, what is the resulting pH?
A solution contains 0.5 moles of acetic acid and 1.0 mole of sodium acetate dissolved, what is the buffer capacity?
A solution contains 0.5 moles of acetic acid and 1.0 mole of sodium acetate dissolved, what is the buffer capacity?
If 100 mL of 0.1 M $LiOH$ is added to 200 mL of 0.1 M formic, what is the resulting pH, given formic acid has a $pK_a$ of 4?
If 100 mL of 0.1 M $LiOH$ is added to 200 mL of 0.1 M formic, what is the resulting pH, given formic acid has a $pK_a$ of 4?
200 mL of 0.2 M ammonia ($K_b = 10^{-5}$) is titrated with 100 mL of 0.4 M $HClO_3$. Which is true?
200 mL of 0.2 M ammonia ($K_b = 10^{-5}$) is titrated with 100 mL of 0.4 M $HClO_3$. Which is true?
Which solution would form a buffer upon mixing?
Which solution would form a buffer upon mixing?
For phosphoric acid ($H_3PO_4$), which of the following expressions would accurately calculate the $K_{a2}$ value?
For phosphoric acid ($H_3PO_4$), which of the following expressions would accurately calculate the $K_{a2}$ value?
5 mole each of BaCO3 and NaHCO3 are thrown into $H_2O$, what is the pH (pKa = 6, 10)
5 mole each of BaCO3 and NaHCO3 are thrown into $H_2O$, what is the pH (pKa = 6, 10)
5 moles of KOH is added to a 1 L solution of 0.5 mol $H_2CO_3$ and 0.5 mol $KHCO_3$, determine the pH (pKa = 6, 10).
5 moles of KOH is added to a 1 L solution of 0.5 mol $H_2CO_3$ and 0.5 mol $KHCO_3$, determine the pH (pKa = 6, 10).
Carbonic acid, a diprotic acid, has $pK_a$ values of approximately 6 and 10. In an alpha diagram, which species dominates at pH 8?
Carbonic acid, a diprotic acid, has $pK_a$ values of approximately 6 and 10. In an alpha diagram, which species dominates at pH 8?
Which system calculates pH with the least error using the weak acid equation?
Which system calculates pH with the least error using the weak acid equation?
What is the approximate pH of 0.01 M $H_2SO_4$ accounting for $K_{a}$ values?
What is the approximate pH of 0.01 M $H_2SO_4$ accounting for $K_{a}$ values?
What is the pH of $10^{-8}$ M $NaOH$?
What is the pH of $10^{-8}$ M $NaOH$?
Flashcards
Net Ionic equation
Net Ionic equation
Shows only the chemical species that react, excluding spectator ions.
Spectator ions
Spectator ions
Ions present on both sides of the equation that do not participate in the reaction.
Molar Solubility
Molar Solubility
A measure of how much a salt dissolves and ionizes in water.
Ksp
Ksp
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Common ion effect
Common ion effect
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Selective Precipitation
Selective Precipitation
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Bronsted Acid
Bronsted Acid
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Bronsted Base
Bronsted Base
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Autoprotolysis of water
Autoprotolysis of water
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Kw
Kw
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pH
pH
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Neutral solution
Neutral solution
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Buffer Solution
Buffer Solution
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Buffer Capacity
Buffer Capacity
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Equivalence point
Equivalence point
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Buffer region
Buffer region
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Polyprotic acid
Polyprotic acid
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Alpha Diagram
Alpha Diagram
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Amphiprotic species
Amphiprotic species
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Equivalence
Equivalence
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Study Notes
- Contains a list of question types (QTs) for CH 302 Solubility and Acid/Base Chemistry
Interpreting Net Ionic Equations and Spectator Ions
- Net ionic reaction indicates chemical species undergoing reaction
- Spectator ions appear on both sides of reaction; do not participate in chemistry
- Solubility rules are needed to recognize soluble and insoluble ions
- Multiply charged species typically insoluble, except sulfates
- Nitrates, chlorates, and ammonium salts are always soluble
- Alkali metals and halogens are generally always soluble, except silver (Ag) salts like AgCl
Estimating Solubility from Ksp
- Salts dissociate to varying degrees in water
- Molar solubility and Ksp indicate how much they dissolve and ionize
- Ksp equilibrium constant that represents the equilibrium between solid salt and dissolved ions
- Molar solubility: amount/concentration of solute in saturated solution at equilibrium
- A small Ksp (large negative exponent) indicates low compound solubility
- The relationship between Ksp and molar solubility depends on the number of ions that dissociate.
Calculating Molar Solubility from Ksp
- This question type focuses on accurate computation instead of estimating using roots
- Divide by coefficient 4, 27, or 108 first
- Math should work itself out easily without a calculator
Common Ion Calculation
- Soluble salt added to an insoluble salt that has an ion in common
- By Le Chatelier's principle, soluble salt dissolution shifts left, making it less soluble
- Steps to solve:
- Identify common ion and insoluble salt (IS).
- Write Ksp expression for the insoluble salt.
- Directly plug in the concentration of the common ion.
- Solve for concentration of the other ion; indicates new molar solubility.
Selective Precipitation
- Three ions floating in water and a mysterious anion is added
- To understand which cation will participate first, consider that is the one with the lowest molar solublity
- Farther apart Ksp values are for the same form (same # ions in the salt), the easier it is to selectively precipitate.
Acid/Base Theory
- Arrhenius Theory: Acids and bases are the dissociation products for water (H3O+ and OH-)
- Brønsted-Lowry Theory: Focuses on the proton, H+
- Brønsted acid: proton (H+) donor
- Brønsted base: proton (H+) acceptor.
- Lewis Theory: Built around the unbonded electron pair
- Lewis base: electron donor with unpaired electrons
- Lewis acid: electron acceptor with empty orbitals
Autoprotolysis of Water
- H2O with no acids or bases added
- Given H2O (I) ⇌ H+ (aq) + OH-(aq), Kw = [H+][OH-] where [H+] = [OH-]
- At room temperature (25°C), Kw = 10-14, [H+] = [OH-] = 10-7 M
- Dissociation of water is negligible as represented by [H+] = [OH-] and pH = pOH
- Water dissociation is endothermic because energy is required to break a bond
- As T increases, Kw increases; as T decreases, Kw decreases
- Water is still neutral because [H+] = [OH-], but pH = 7 only at 25°C
Navigating the Acid/Base Terrain
- There are conversions between pH, pOH, [H+], [OH-], pKa, pKb, Ka and Kb
- pH = -log[H+]
- pOH = -log[OH-]
- Kw = [H+][OH-] = 10-14 at 25°C
- pKw = pH + pOH = 14 at 25°C
- pKa = -log(Ka)
- pKb = -log(Kb)
- Kw = KaKb = 10-14 at 25°C
- pKw = pKa + pKb = 14 at 25°C
Ranking Acidity and Basicity based on K Values
- The larger the Ka (= smaller pKa), the stronger the acid
- The larger the K♭ (= smaller pK♭), the stronger the base
- Keep in mind you may be provided with acids and asked about their conjugate bases, or vice versa. Kw = KaKb, thus “the stronger the acid, the weaker the conjugate base” (and vice versa)
Equilibrium Acid/Base Calculation: Strong Case
- Equilibrium calculation because there is no RICE table needed since there is no reaction occurring
- Memorize the 7 strong acids and 6 strong bases by formula and name
- Strong Acids: HCl, HBr, HI, HNO3, H2SO4, HClO3, HClO4
- Strong Bases: LiOH, NaOH, KOH, RbOH, Ba(OH)2, Sr(OH)2
- Remove spectator ions, then for strong a/b only H⁺ or OH¯ remains.
- Convert to pH to answer the question.
Equilibrium Acid/Base Calculation: Weak Case
- Simple weak acid/base calculation involves simply dumping a weak acid or base into water and asking the pH
- Remove spectator ions
- Identify compound as strong or weak acid or base and its form: H+, OH-, НА, А¯, BH⁺, or B.
- No neutralization happening in the "simple" case, so just solve the appropriate calculation
- Weak Acid: [H+] = (KaCa)1/2
- Weak Base: [OH¯] = (К♭С♭)1/2
- Convert to pH, pOH, [H+], or [OH¯] as requested to answer the question
Equilibrium Acid/Base Calculation: Buffer
- The simple buffer acid/base calculation involves dumping a weak acid/base and its conjugate base/acid into water to create a buffer and asking the pH
- There is no neutralization happening in the "simple" case, so just solve the appropriate calculation
- Equations for buffer
- [H+] = Kaa
- [OH-] = Kob
- Convert to pH, pOH, [H+], or [OH-] as requested
Neutralization: Strong Acid/Strong Base Case
- After any spectator ions are removed, use neutralizaiton calculations dor strong acids/bases
- The following neutralization reactions take place: H+ + OH- → H¬2O
- Identify compounds as strong or weak acid or base and its form: H+, OH¯, HA, A¯, BH⁺, or B. For buffers, recognize that the compounds are conjugates.
- Do you neutralize? Yes if there is an acid + base and at least one is strong
- Set up a RICE table, converting to moles, and solve the limiting reagent problem
- Identify what type of solution remains and solve the appropriate calculation
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