AP Chemistry Flashcards: Acid Base Reactions And Buffers

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This deck focuses on Acid Base Reactions And Buffers, giving you a quick way to review the definitions, rules, and examples that matter most for AP Chemistry.

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Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: Identify the weak base in the ammonia-ammonium chloride buffer system.

Answer: Ammonia ($NH_3$). Weak base component that partially ionizes.

Flashcard 2: Which strong base completely dissociates in water?

Answer: Sodium hydroxide ($NaOH$). Strong base with 100% dissociation in water.

Flashcard 3: What is the effect of adding a strong acid to a buffer solution?

Answer: Buffer resists significant pH change. Buffer neutralizes acid through base component reaction.

Flashcard 4: What is the formula for calculating pH from hydrogen ion concentration?

Answer: p$H = -\text{log}[H^+]$. Negative log transforms $H^+$ concentration to pH scale.

Flashcard 5: What is the $K_a$ expression for acetic acid $CH_3COOH$?

Answer: $K_a = \frac{[CH_3COO^-][H^+]}{[CH_3COOH]}$. Products over reactants for acid dissociation equilibrium.

Flashcard 6: Identify the conjugate acid of the base $H_2O$.

Answer: $H_3O^+$. Water gains a proton to form hydronium ion.

Flashcard 7: Identify the weak acid in the acetic acid-sodium acetate buffer system.

Answer: Acetic acid ($CH_3COOH$). Weak acid component that partially ionizes.

Flashcard 8: State the Bronsted-Lowry definition of an acid.

Answer: Proton donor. Acids release protons to other species in solution.

Flashcard 9: Which ion is the conjugate acid of $NH_2^-$?

Answer: $NH_3$. Gains a proton to form ammonia from amide ion.

Flashcard 10: What happens to the pH of a buffer when a small amount of acid is added?

Answer: pH decreases slightly. Buffer components neutralize added acid effectively.

Flashcard 11: Calculate the $pK_a$ for an acid with $K_a = 1.0 \times 10^{-5}$.

Answer: $pK_a = 5$. $pK_a = -\log(1.0 \times 10^{-5}) = 5$.

Flashcard 12: Determine the pH if $[H^+] = 2.5 \times 10^{-4} M$.

Answer: pH = 3.60. pH = $-\log(2.5 \times 10^{-4}) = 3.60$.

Flashcard 13: Identify the weak acid in the acetic acid-sodium acetate buffer system.

Answer: Acetic acid ($CH_3COOH$). Weak acid component that partially ionizes.

Flashcard 14: What is the formula for calculating $pK_w$?

Answer: $pK_w = pH + pOH$. Sum equals 14 at 25°C for aqueous solutions.

Flashcard 15: Identify the conjugate acid of the base $NH_3$.

Answer: $NH_4^+$. Gains a proton from $NH_3$ to form ammonium ion.

Flashcard 16: What is the effect of dilution on the pH of a buffer?

Answer: Minimal change in pH. Buffer ratio remains constant during dilution process.

Flashcard 17: Calculate the pH if $[OH^-] = 1.0 \times 10^{-5} M$ at 25°C.

Answer: pH = 9. pOH = 5, so pH = 14 - 5 = 9.

Flashcard 18: What is the concentration of $H^+$ in a solution with pH 4?

Answer: $1.0 \times 10^{-4} M$. $[H^+] = 10^{-4} = 1.0 \times 10^{-4}$ M.

Flashcard 19: Identify the conjugate base of the acid $H_2O$.

Answer: $OH^-$. Water loses a proton to form hydroxide ion.

Flashcard 20: Which strong acid completely dissociates in water?

Answer: Hydrochloric acid ($HCl$). Strong acid with 100% ionization in water.

Flashcard 21: Identify the conjugate base of the acid $HCl$.

Answer: $Cl^-$. Loses a proton from $HCl$ to form chloride ion.

Flashcard 22: Which strong acid completely dissociates in water?

Answer: Hydrochloric acid ($HCl$). Strong acid with 100% ionization in water.

Flashcard 23: What is the formula to calculate pOH from hydroxide ion concentration?

Answer: p$OH = -\text{log}[OH^-]$. Negative log transforms $OH^-$ concentration to pOH scale.

Flashcard 24: What is the $K_a$ expression for acetic acid $CH_3COOH$?

Answer: $K_a = \frac{[CH_3COO^-][H^+]}{[CH_3COOH]}$. Products over reactants for acid dissociation equilibrium.

Flashcard 25: Which ion is the conjugate acid of $NH_2^-$?

Answer: $NH_3$. Gains a proton to form ammonia from amide ion.

Flashcard 26: Calculate the pH change when $0.01$ mol $HCl$ is added to a 1L buffer with $pK_a = 4.76$.

Answer: Minimal pH change. Buffer capacity prevents large pH shifts effectively.

Flashcard 27: State the Bronsted-Lowry definition of a base.

Answer: Proton acceptor. Bases accept protons from other species in solution.

Flashcard 28: Identify the conjugate base of the acid $H_2O$.

Answer: $OH^-$. Water loses a proton to form hydroxide ion.

Flashcard 29: What characteristic of a weak acid makes it suitable for a buffer?

Answer: Partial ionization. Incomplete dissociation provides buffering capacity.

Flashcard 30: Calculate the pH of a solution with $[H^+] = 1.0 \times 10^{-3} M$.

Answer: pH = 3. pH = $-\log(1.0 \times 10^{-3}) = 3$.

Flashcard 31: Calculate the pH of a buffer with $pK_a = 4.76$ and $\frac{[A^-]}{[HA]} = 1$.

Answer: pH = 4.76. When ratio equals 1, $\log(1) = 0$, so pH = $pK_a$.

Flashcard 32: What is the formula to calculate pOH from hydroxide ion concentration?

Answer: p$OH = -\text{log}[OH^-]$. Negative log transforms $OH^-$ concentration to pOH scale.

Flashcard 33: What is the pH of a neutral solution at 25°C?

Answer: pH = 7. Equal concentrations of $H^+$ and $OH^-$ ions.

Flashcard 34: What defines a buffer solution?

Answer: Resists changes in pH upon addition of acid or base. Weak acid-base pair maintains stable pH range.

Flashcard 35: Calculate the pH change when $0.01$ mol $HCl$ is added to a 1L buffer with $pK_a = 4.76$.

Answer: Minimal pH change. Buffer capacity prevents large pH shifts effectively.

Flashcard 36: Calculate the pOH of a solution with $[OH^-] = 1.0 \times 10^{-4} M$.

Answer: pOH = 4. pOH = $-\log(1.0 \times 10^{-4}) = 4$.

Flashcard 37: What happens to the pH of a buffer when a small amount of acid is added?

Answer: pH decreases slightly. Buffer components neutralize added acid effectively.

Flashcard 38: What is the primary function of a buffer?

Answer: To maintain stable pH. Prevents large pH changes in chemical systems.

Flashcard 39: What is the relationship between $K_a$ and $K_b$ for a conjugate acid-base pair?

Answer: $K_a \times K_b = K_w$. Product equals water's ionization constant at 25°C.

Flashcard 40: What is the value of $K_w$ at 25°C?

Answer: $1.0 \times 10^{-14}$. Water's ionization constant at standard temperature.

Flashcard 41: Identify the weak base in the ammonia-ammonium chloride buffer system.

Answer: Ammonia ($NH_3$). Weak base component that partially ionizes.

Flashcard 42: Identify the components of a buffer solution.

Answer: Weak acid and its conjugate base. Both species neutralize added acids and bases.

Flashcard 43: State the Bronsted-Lowry definition of a base.

Answer: Proton acceptor. Bases accept protons from other species in solution.

Flashcard 44: What defines a buffer solution?

Answer: Resists changes in pH upon addition of acid or base. Weak acid-base pair maintains stable pH range.

Flashcard 45: Calculate the pOH of a solution with $[OH^-] = 1.0 \times 10^{-4} M$.

Answer: pOH = 4. pOH = $-\log(1.0 \times 10^{-4}) = 4$.

Flashcard 46: What is the formula for calculating $pK_w$?

Answer: $pK_w = pH + pOH$. Sum equals 14 at 25°C for aqueous solutions.

Flashcard 47: Which ion is the conjugate base of $H_3PO_4$?

Answer: $H_2PO_4^-$. Loses one proton from phosphoric acid.

Flashcard 48: What is the $K_b$ expression for ammonia $NH_3$?

Answer: $K_b = \frac{[NH_4^+][OH^-]}{[NH_3]}$. Products over reactants for base ionization equilibrium.

Flashcard 49: Identify the conjugate acid of the base $H_2O$.

Answer: $H_3O^+$. Water gains a proton to form hydronium ion.

Flashcard 50: What is the effect of adding a strong acid to a buffer solution?

Answer: Buffer resists significant pH change. Buffer neutralizes acid through base component reaction.

Flashcard 51: What is the primary function of a buffer?

Answer: To maintain stable pH. Prevents large pH changes in chemical systems.

Flashcard 52: Calculate the $pK_a$ for an acid with $K_a = 1.0 \times 10^{-5}$.

Answer: $pK_a = 5$. $pK_a = -\log(1.0 \times 10^{-5}) = 5$.

Flashcard 53: Calculate the pH of a solution with $[H^+] = 1.0 \times 10^{-3} M$.

Answer: pH = 3. pH = $-\log(1.0 \times 10^{-3}) = 3$.

Flashcard 54: What is the Henderson-Hasselbalch equation for pH?

Answer: $\mathrm{pH} = \mathrm{p}K_a + \log \frac{[A^-]}{[HA]}$. Relates buffer pH to acid strength and base ratio.

Flashcard 55: What is the concentration of $H^+$ in a solution with pH 4?

Answer: $1.0 \times 10^{-4} M$. $[H^+] = 10^{-4} = 1.0 \times 10^{-4}$ M.

Flashcard 56: Calculate the pH if $[OH^-] = 1.0 \times 10^{-5} M$ at 25°C.

Answer: pH = 9. pOH = 5, so pH = 14 - 5 = 9.

Flashcard 57: Identify the conjugate acid of the base $NH_3$.

Answer: $NH_4^+$. Gains a proton from $NH_3$ to form ammonium ion.

Flashcard 58: Calculate the pH of a buffer with $pK_a = 4.76$ and $\frac{[A^-]}{[HA]} = 1$.

Answer: pH = 4.76. When ratio equals 1, $\log(1) = 0$, so pH = $pK_a$.

Flashcard 59: Determine the pH if $[H^+] = 2.5 \times 10^{-4} M$.

Answer: pH = 3.60. pH = $-\log(2.5 \times 10^{-4}) = 3.60$.

Flashcard 60: What is the pH of a neutral solution at 25°C?

Answer: pH = 7. Equal concentrations of $H^+$ and $OH^-$ ions.

Flashcard 61: Which strong base completely dissociates in water?

Answer: Sodium hydroxide ($NaOH$). Strong base with 100% dissociation in water.

Flashcard 62: Find the pH of a 0.1 M $HCl$ solution.

Answer: pH = 1. Strong acid completely ionizes: $[H^+] = 0.1$ M.

Flashcard 63: Identify the conjugate base of the acid $HCl$.

Answer: $Cl^-$. Loses a proton from $HCl$ to form chloride ion.

Flashcard 64: Which ion is the conjugate base of $H_3PO_4$?

Answer: $H_2PO_4^-$. Loses one proton from phosphoric acid.

Flashcard 65: Find the pH of a 0.1 M $HCl$ solution.

Answer: pH = 1. Strong acid completely ionizes: $[H^+] = 0.1$ M.

Flashcard 66: Identify the components of a buffer solution.

Answer: Weak acid and its conjugate base. Both species neutralize added acids and bases.

Flashcard 67: What is the $K_b$ expression for ammonia $NH_3$?

Answer: $K_b = \frac{[NH_4^+][OH^-]}{[NH_3]}$. Products over reactants for base ionization equilibrium.

Flashcard 68: What characteristic of a weak acid makes it suitable for a buffer?

Answer: Partial ionization. Incomplete dissociation provides buffering capacity.

Flashcard 69: Which ion is responsible for the acidity of a solution?

Answer: Hydrogen ion ($H^+$). Higher $H^+$ concentration means more acidic solution.

Flashcard 70: State the Bronsted-Lowry definition of an acid.

Answer: Proton donor. Acids release protons to other species in solution.