Chapter 2.3: How Strong Are Acid or Base Solutions?

Understanding pH scale and measuring acid-base strength

🔬 The pH Scale
The pH scale measures hydrogen ion concentration from 0 (very acidic) to 14 (very basic). pH 7 is neutral. The 'p' in pH stands for 'potenz' in German, meaning power.

The pH Scale

Measure the strength of acids and bases

0 - Strong Acid 7 - Neutral 14 - Strong Base
Explore pH and Acid-Base Strength
🔬 Activity 2.11: Test pH Values of Solutions
Solution Color with Indicator Approximate pH Nature
Saliva (before meal) Light Green 7.4 Slightly Basic
Lemon juice Red 2.2 Acidic
Water Green 7.0 Neutral
Milk of Magnesia Blue 10.5 Basic
Sodium Hydroxide Purple 13.0 Strongly Basic
🌱 pH in Everyday Life
  • 🧬 Human Body: Works within pH 7.0-7.8
  • 🦷 Tooth Decay: Starts when mouth pH < 5.5
  • 🌧️ Acid Rain: Rain with pH < 5.6
  • 🌿 Plant Growth: Different plants need specific pH ranges
  • 🐝 Bee Sting: Contains acid (use baking soda)
  • 🌾 Soil Treatment: Farmers use lime for acidic soil