Summary of Temperature Effects on Water Ionization

Effect of Temperature on Ionization of Water

• Conductivity of Water

  • Low temperature: Low conductivity
  • High temperature: Increased conductivity due to higher ionization

• Ion Concentrations

  • At 25°C:
  • [H₃O⁺] = [OH⁻] = 1 \times 10^{-7} M
  • Conductivity is low
  • At 60°C:
  • [H₃O⁺] = [OH⁻] ≈ 3.1 \times 10^{-7} M
  • Increased conductivity
  • Water remains neutral as [H₃O⁺] = [OH⁻]

• Le Chatelier's Principle

  • Ionization of water is endothermic
  • Increased temperature shifts equilibrium to the right:
  • Result: Higher concentrations of H₃O⁺ and OH⁻

• Kw Value

  • At 25°C:
  • K_w = [H₃O⁺][OH⁻] = 1 \times 10^{-14}
  • Above 25°C:
  • [H₃O⁺] and [OH⁻] increase, K_w > 1 \times 10^{-14}
  • Below 25°C:
  • [H₃O⁺] and [OH⁻] decrease, K_w < 1 \times 10^{-14}

• Summary of Temperature Effects

  • At 25°C:
  • [H₃O⁺] = [OH⁻] = 1 \times 10^{-7} ; Kw = 1 \times 10^{-14} ; Neutral
  • Above 25°C:
  • Both concentrations > 1 \times 10^{-7} M; K_w > 1 \times 10^{-14} ; Neutral
  • Below 25°C:
  • Both concentrations < 1 \times 10^{-7} M; K_w < 1 \times 10^{-14} ; Neutral

• Key Takeaway

  • Water remains neutral at all temperatures as the concentrations of hydronium and hydroxide ions are equal.