AP Chemistry Flashcards: Acid Base Reactions And Buffers

What this deck covers

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.

How to use these flashcards

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: Which strong base completely dissociates in water?

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

Flashcard 2: 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 3: Identify the conjugate acid of the base $H_2O$.

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

Flashcard 4: Which ion is the conjugate acid of $NH_2^-$?

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

Flashcard 5: 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 6: 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 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: What is the formula for calculating $pK_w$?

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

Flashcard 9: 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 10: 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 11: Identify the conjugate base of the acid $H_2O$.

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

Flashcard 12: Which strong acid completely dissociates in water?

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

Flashcard 13: Identify the conjugate base of the acid $HCl$.

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

Flashcard 14: 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 15: 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 16: 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 17: 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 18: 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 19: What is the primary function of a buffer?

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

Flashcard 20: 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 21: What is the value of $K_w$ at 25°C?

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

Flashcard 22: Identify the weak base in the ammonia-ammonium chloride buffer system.

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

Flashcard 23: Identify the components of a buffer solution.

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

Flashcard 24: State the Bronsted-Lowry definition of a base.

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

Flashcard 25: 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 26: 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 27: 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 28: 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 29: 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 30: 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 31: Identify the conjugate acid of the base $NH_3$.

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

Flashcard 32: What is the pH of a neutral solution at 25°C?

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

Flashcard 33: Find the pH of a 0.1 M $HCl$ solution.

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

Flashcard 34: Which ion is the conjugate base of $H_3PO_4$?

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

Flashcard 35: 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 36: What characteristic of a weak acid makes it suitable for a buffer?

Answer: Partial ionization. Incomplete dissociation provides buffering capacity.

Flashcard 37: Which ion is responsible for the acidity of a solution?

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

Flashcard 38: State the Bronsted-Lowry definition of an acid.

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