Molecular Structure of Acids and Bases - AP Chemistry
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What is the Henderson-Hasselbalch equation for pOH?
What is the Henderson-Hasselbalch equation for pOH?
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$pOH = pK_b + \log\left(\frac{[BH⁺]}{[B]}\right)$. Relates buffer pOH to base/acid ratio.
$pOH = pK_b + \log\left(\frac{[BH⁺]}{[B]}\right)$. Relates buffer pOH to base/acid ratio.
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What is the Henderson-Hasselbalch equation for pH?
What is the Henderson-Hasselbalch equation for pH?
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$pH = pK_a + \log\left(\frac{[A^{-}]}{[HA]}\right)$. Relates buffer pH to acid/base ratio.
$pH = pK_a + \log\left(\frac{[A^{-}]}{[HA]}\right)$. Relates buffer pH to acid/base ratio.
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Identify the common ion in a mixture of HCl and NaCl.
Identify the common ion in a mixture of HCl and NaCl.
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Cl⁻. Both compounds contain chloride ions.
Cl⁻. Both compounds contain chloride ions.
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List one example of a weak base.
List one example of a weak base.
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Ammonia (NH₃). A common weak base that accepts protons from water.
Ammonia (NH₃). A common weak base that accepts protons from water.
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Define the term 'amphoteric'.
Define the term 'amphoteric'.
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A species that can act as both an acid and a base. Can donate or accept protons depending on conditions.
A species that can act as both an acid and a base. Can donate or accept protons depending on conditions.
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Define the term 'strong acid'.
Define the term 'strong acid'.
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An acid that completely dissociates in solution. Nearly 100% ionization occurs in aqueous solution.
An acid that completely dissociates in solution. Nearly 100% ionization occurs in aqueous solution.
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State the relationship between pH and pOH.
State the relationship between pH and pOH.
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$pH + pOH = 14$. This relationship holds at 25°C due to $K_w$.
$pH + pOH = 14$. This relationship holds at 25°C due to $K_w$.
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Identify the Lewis acid in AlCl₃ + Cl⁻ → AlCl₄⁻.
Identify the Lewis acid in AlCl₃ + Cl⁻ → AlCl₄⁻.
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AlCl₃. $AlCl_3$ accepts the electron pair from $Cl^-$.
AlCl₃. $AlCl_3$ accepts the electron pair from $Cl^-$.
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What is the Lewis definition of an acid?
What is the Lewis definition of an acid?
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A species that accepts an electron pair. Lewis theory focuses on electron pair interactions, not protons.
A species that accepts an electron pair. Lewis theory focuses on electron pair interactions, not protons.
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What is the pH of a solution with $[H⁺] = 1 \times 10^{-3}$ M?
What is the pH of a solution with $[H⁺] = 1 \times 10^{-3}$ M?
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- Using $pH = -\log(1 \times 10^{-3}) = 3$.
- Using $pH = -\log(1 \times 10^{-3}) = 3$.
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Define the term 'strong base'.
Define the term 'strong base'.
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A base that completely dissociates in solution. Nearly 100% ionization occurs in aqueous solution.
A base that completely dissociates in solution. Nearly 100% ionization occurs in aqueous solution.
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What is the pOH of a solution with $[OH⁻] = 1 \times 10^{-5}$ M?
What is the pOH of a solution with $[OH⁻] = 1 \times 10^{-5}$ M?
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- Using $pOH = -\log(1 \times 10^{-5}) = 5$.
- Using $pOH = -\log(1 \times 10^{-5}) = 5$.
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Define the term 'weak acid'.
Define the term 'weak acid'.
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An acid that partially dissociates in solution. Only a small percentage ionizes in aqueous solution.
An acid that partially dissociates in solution. Only a small percentage ionizes in aqueous solution.
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What is the definition of a Bronsted-Lowry acid?
What is the definition of a Bronsted-Lowry acid?
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A species that donates a proton (H⁺). This is the proton transfer definition used in acid-base chemistry.
A species that donates a proton (H⁺). This is the proton transfer definition used in acid-base chemistry.
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Identify an example of an amphoteric substance.
Identify an example of an amphoteric substance.
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Water (H₂O). Can act as acid or base in different reactions.
Water (H₂O). Can act as acid or base in different reactions.
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State the relationship between $K_a$ and $K_b$ for conjugate pairs.
State the relationship between $K_a$ and $K_b$ for conjugate pairs.
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$K_a \times K_b = K_w$. This relationship connects conjugate acid-base pairs.
$K_a \times K_b = K_w$. This relationship connects conjugate acid-base pairs.
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What is the Lewis definition of a base?
What is the Lewis definition of a base?
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A species that donates an electron pair. Lewis bases are electron pair donors in chemical reactions.
A species that donates an electron pair. Lewis bases are electron pair donors in chemical reactions.
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What is the pH of a buffer with equal concentrations of acid and base?
What is the pH of a buffer with equal concentrations of acid and base?
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pH = pK_a. When $\log(1) = 0$, so pH equals $pK_a$.
pH = pK_a. When $\log(1) = 0$, so pH equals $pK_a$.
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What is the effect of dilution on the pH of a buffer?
What is the effect of dilution on the pH of a buffer?
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Minimal change in pH. Buffer capacity maintains pH despite concentration changes.
Minimal change in pH. Buffer capacity maintains pH despite concentration changes.
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What does a large $K_a$ value indicate about an acid?
What does a large $K_a$ value indicate about an acid?
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The acid is strong, dissociating more in solution. Large $K_a$ means greater ionization tendency.
The acid is strong, dissociating more in solution. Large $K_a$ means greater ionization tendency.
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What is the general formula for calculating pH?
What is the general formula for calculating pH?
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$pH = -\log[H^+]$. Negative log of hydrogen ion concentration.
$pH = -\log[H^+]$. Negative log of hydrogen ion concentration.
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Which is stronger: HCl or HF?
Which is stronger: HCl or HF?
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HCl. HCl is a strong acid; HF is weak.
HCl. HCl is a strong acid; HF is weak.
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What is the primary component of stomach acid?
What is the primary component of stomach acid?
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Hydrochloric acid (HCl). Gastric acid is primarily HCl with pH around 1-2.
Hydrochloric acid (HCl). Gastric acid is primarily HCl with pH around 1-2.
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What is the definition of a Bronsted-Lowry base?
What is the definition of a Bronsted-Lowry base?
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A species that accepts a proton (H⁺). This is the proton acceptor definition in Bronsted-Lowry theory.
A species that accepts a proton (H⁺). This is the proton acceptor definition in Bronsted-Lowry theory.
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Which is the conjugate base of H₂SO₄?
Which is the conjugate base of H₂SO₄?
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HSO₄⁻. $H_2SO_4$ loses one proton to form $HSO_4^-$.
HSO₄⁻. $H_2SO_4$ loses one proton to form $HSO_4^-$.
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Identify the Lewis base in NH₃ + BF₃ → NH₃BF₃.
Identify the Lewis base in NH₃ + BF₃ → NH₃BF₃.
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NH₃. $NH_3$ donates its lone pair to $BF_3$.
NH₃. $NH_3$ donates its lone pair to $BF_3$.
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What does a small $K_a$ value indicate about an acid?
What does a small $K_a$ value indicate about an acid?
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The acid is weak, dissociating less in solution. Small $K_a$ means lower ionization tendency.
The acid is weak, dissociating less in solution. Small $K_a$ means lower ionization tendency.
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Identify the conjugate base of HCl.
Identify the conjugate base of HCl.
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Cl⁻. Formed when HCl loses its proton ($H^+$).
Cl⁻. Formed when HCl loses its proton ($H^+$).
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What is the formula for the base dissociation constant, $K_b$?
What is the formula for the base dissociation constant, $K_b$?
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$K_b = \frac{[BH^+][OH^-]}{[B]}$. Measures the extent of base dissociation in solution.
$K_b = \frac{[BH^+][OH^-]}{[B]}$. Measures the extent of base dissociation in solution.
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List one example of a strong acid.
List one example of a strong acid.
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Hydrochloric acid (HCl). One of the seven common strong acids.
Hydrochloric acid (HCl). One of the seven common strong acids.
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