pH 14-0 12- 10- 8 6 4- 2- Puzzle: pH Graph of Different Compounds 0: 1e-14 Sodium bicarbonate Oven cleaner Soapy water Ammonia Bleach Coffee 1e-12 Antacids. Sea water Baking soda Beer Cytoplasm 1e-10 Pure water. Human blood 1e-06 1e-04 H+ concentration (in moles per liter) 1e-08 Lake Natron Lemon juice Sodium Hydroxide Vinegar Battery acid 0.01 Stomach acid 1
The correct answer and explanation is:
The correct answer involves identifying the pH values of various substances based on their H⁺ concentration and understanding their placement on the pH scale.
Correct Answer:
- pH 0-1: Battery acid, stomach acid
- pH 2-3: Vinegar, lemon juice
- pH 4-5: Coffee
- pH 6-7: Pure water, human blood
- pH 8-9: Sea water, baking soda
- pH 10-11: Soapy water, antacids
- pH 12-13: Ammonia, bleach
- pH 14: Sodium hydroxide (NaOH), oven cleaner
Explanation:
The pH scale measures the acidity or basicity of a solution, ranging from 0 (most acidic) to 14 (most basic). It is logarithmic, meaning each step represents a tenfold difference in H⁺ concentration.
- Acids (pH < 7):
- Battery acid and stomach acid (pH 0-1) are highly acidic with very high concentrations of H⁺ ions (H+H⁺ ≈ 1 M for pH 0).
- Lemon juice and vinegar (pH 2-3) are less acidic but still contain significant H⁺ ion concentrations, common in weak organic acids.
- Neutral (pH ≈ 7):
- Pure water (neutral, pH 7) has an equal balance of H⁺ and OH⁻ ions. Human blood (slightly alkaline, pH ~7.4) is closely regulated to maintain this balance.
- Bases (pH > 7):
- Baking soda and sea water (pH 8-9) are mild bases, with lower H⁺ ion concentrations.
- Soapy water and antacids (pH 10-11) neutralize acids and have moderately low H⁺ ion concentrations.
- Strong bases like ammonia and bleach (pH 12-13) and sodium hydroxide (pH 14) contain extremely low H⁺ ion concentrations (H+H⁺ < 10−1310^{-13}).
The relationship between pH and H⁺ concentration is governed by the formula: pH=−log10[H⁺]pH = -\log_{10}[\text{H⁺}]
For example, a solution with H+H⁺ = 10−610^{-6} M has a pH of 6. This understanding allows classification of substances based on their acidity or alkalinity.