CP12 Investigating pH Changes

• What is the pH range over which universal indicators change color?

  0-14
• Universal indicators provide more precise pH readings than pH meters.

  False
• The formula for calculating pH is: $\text{pH} =$$- \log_{10} [H + ]$, where [H + ]</latex> is the hydrogen ion concentration
• Order the phases of a titration of a strong acid with a strong base based on pH range.

  1️⃣ Initial (pH < 3)

  2️⃣ Early Neutralization (pH 3-6)

  3️⃣ Equivalence Point (pH 7)

  4️⃣ Late Neutralization (pH 8-11)

  5️⃣ Excess NaOH (pH > 11)
• What happens to the pH during the equivalence point in a strong acid-strong base titration?

  It reaches 7
• Weak acids and bases dissociate completely in water.

  False
• Weak acid-base titrations exhibit gradual pH changes near the equivalence
• Match the phase of a weak acid-strong base titration with its key characteristic:

  Initial Phase ↔️ Higher initial pH due to incomplete dissociation

  Buffering Region ↔️ Slow pH change

  Equivalence Point ↔️ pH not 7 due to hydrolysis

  Excess Strong Base ↔️ pH rapidly increases
• What two components must be present for a buffering effect to occur in a weak acid-base mixture?

  Weak acid and its conjugate base
• What does pH measure on a scale from 0 to 14?

  Acidity or alkalinity
• Acidic solutions have a pH less than 7.
• Neutral solutions have a pH of exactly 7
• What are two methods to measure pH?

  pH indicators and meters
• pH indicators provide less accurate pH readings compared to pH meters.
• Match the pH measurement method with its accuracy:

  pH Meters ↔️ More accurate

  pH Indicators ↔️ Less accurate
• To prepare acidic solutions, use hydrochloric acid, whereas alkaline solutions require sodium hydroxide
• What molar concentration of HCl is used to achieve a pH of 3?

  0.001 M
• A phosphate buffer is used to maintain a neutral pH of 7.
• What molar concentration of NaOH is used to achieve a pH of 8?

  $1 \times 10^{ - 6} \text{ M}$
• Match the solution type with its buffer solution:

  Acidic ↔️ Citrate Buffer

  Neutral ↔️ Phosphate Buffer

  Alkaline ↔️ Borate or Carbonate Buffer
• pH meters must be calibrated using buffer solutions of known pH
• What is a typical calibration range for pH meters using buffer solutions?

  pH 4 and pH 10
• Universal indicators are better for quantitative analysis compared to pH meters.

  False
• What is the formula for calculating pH?

  $\text{pH} =$$- \log_{10} [H + ]$
• Match the pH measurement method with its description:

  pH Indicators ↔️ Change color at different pH levels

  pH Meters ↔️ Measure pH with high precision
• Buffer solutions are used to maintain consistent pH levels when preparing solutions.
• What molar concentration of HCl is used to achieve a pH of 3?

  0.001 M
• To achieve a pH of 12 using NaOH, the molar concentration needed is 0.001 M.
• A typical calibration of a pH meter uses buffer solutions at pH 4 and pH 10.
• pH meters must be calibrated using buffer solutions of known pH values
• What pH range characterizes the buffering region in a weak acid-strong base titration?

  4-6
• At the equivalence point in a weak acid-strong base titration, the pH is not 7 due to hydrolysis
• In a titration of a weak acid with a strong base, the pH increases rapidly after the excess strong base phase.
• What does the buffering effect in a weak acid-base system resist?

  Significant pH changes
• pH changes using weak acids and bases differ from strong acids and bases due to their incomplete dissociation
• Weak acid-base titrations show gradual pH changes compared to the sharp transitions near the equivalence point in strong acid-base titrations.
• Phases in the titration of a weak acid with a strong base

  1️⃣ Initial: Weak Acid (pH 3-5)

  2️⃣ Buffering Region: Weak Acid and Its Conjugate Base (pH 4-6)

  3️⃣ Equivalence Point: Balanced Weak Acid and Strong Base (pH 8-9)

  4️⃣ Excess Strong Base: Primarily Strong Base (pH 11-12)
• What is the pH range of a neutral solution?

  7
• The pH is calculated using the formula \text{pH} = - \log_{10} [H + ]</latex>.
• Buffer solutions are used to maintain a consistent pH