4.2.4 The pH scale and neutralization

• The pH scale ranges from 0 to 14.
• Neutralization reactions occur when an acid reacts with a base to form salt and water.
• Order the solution types based on their pH range from lowest to highest:

  1️⃣ Acidic (0 to < 7)

  2️⃣ Neutral (7)

  3️⃣ Basic/Alkaline (> 7 to 14)
• A pH of 7 indicates a neutral solution.
• What is the approximate pH of lemon juice?

  2
• Household bleach is alkaline with a pH of approximately 12.

  True
• What type of ions are present in high concentrations in acidic solutions?

  Hydrogen ions (H+)
• Neutralization always results in a pH of exactly 7.

  False
• A pH value above 7 indicates an acidic solution.

  False
• Match the solution type with its characteristics:

  Acidic ↔️ Tastes sour, reacts with metals

  Neutral ↔️ Tastes bland, does not react strongly

  Basic/Alkaline ↔️ Tastes bitter, feels slippery
• The pH value of 7 indicates a neutral solution.
• What is the pH of pure water?

  7
• Match the solution type with its characteristics:

  Acidic ↔️ Sour taste, reacts with metals

  Neutral ↔️ Bland taste, does not react strongly

  Basic/Alkaline ↔️ Bitter taste, feels slippery
• What ion is present in high concentration in acidic solutions?

  Hydrogen ions (H+)
• The reaction between HCl and NaOH results in a solution with a neutral pH.

  True
• Match the acid and base pairs with their resulting salt:

  HCl + NaOH ↔️ NaCl

  H₂SO₄ + KOH ↔️ K₂SO₄

  HNO₃ + Ca(OH)₂ ↔️ Ca(NO₃)₂
• Lime is used to neutralize acidic soil.
• What does pH measure?

  Acidity or basicity
• A solution with a pH of 7 is acidic.

  False
• What are the products of a neutralization reaction?

  Salt and water
• Match the solution type with its corresponding pH range:

  Acidic ↔️ 0 to < 7

  Neutral ↔️ 7

  Basic/Alkaline ↔️ > 7 to 14
• Lower H+ concentration indicates stronger acidity.

  False
• Pure water has a pH of exactly 7.
• Match the solution type with its pH characteristics:

  Acidic ↔️ High H+ concentration

  Neutral ↔️ H+ concentration = 1 x 10^-7 M

  Basic/Alkaline ↔️ Low H+ concentration
• Neutralization reactions bring the pH of a solution closer to 7.
• What is the balanced chemical equation for the neutralization of hydrochloric acid (HCl) with sodium hydroxide (NaOH)?

  HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
• The pH scale measures the acidity or basicity of a solution, ranging from 0 to 14.
• What is the range of the pH scale?

  0 to 14
• Lemon juice with a pH of 2 is highly acidic.


  True
• The pH scale measures the acidity or basicity of a solution.
• Household bleach with a pH of 12 is alkaline.


  True
• Neutralization reactions bring the pH of the solution closer to 7.
• What type of reaction occurs when an acid and a base combine?

  Neutralization
• What is the role of antacids in the body?

  Neutralize stomach acid