Table of contents

1. The Chemical World9m
- The Scientific Method
  9m
2. Measurement and Problem Solving2h 19m
3. Matter and Energy2h 15m
4. Atoms and Elements2h 33m
5. Molecules and Compounds1h 50m
6. Chemical Composition1h 23m
7. Chemical Reactions1h 43m
8. Quantities in Chemical Reactions1h 8m
9. Electrons in Atoms and the Periodic Table2h 32m
10. Chemical Bonding2h 10m
11 Gases2h 7m
12. Liquids, Solids, and Intermolecular Forces1h 11m
13. Solutions3h 1m
14. Acids and Bases2h 14m
15. Chemical Equilibrium1h 27m
16. Oxidation and Reduction1h 33m
17. Radioactivity and Nuclear Chemistry53m

14. Acids and Bases

The pH Scale

Introduction to Chemistry

14. Acids and Bases

The pH Scale

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Multiple Choice

Which of the following statements about aqueous solutions is/are true?

For an basic solution the concentration of H₃O⁺ is greater than the concentration of OH^-.

The pH of a neutral aqueous solution is 7.00 at all temperatures.

An acidic solution under normal conditions has a pH value less than 7.00.

If the concentration of H₃O⁺ decreases then the concentration of OH^- will also decrease.

The pH of aqueous solutions is less than 7.

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Verified step by step guidance

Step 1: Understand the concept of pH and its relation to H3O+ and OH- concentrations. pH is a measure of the acidity or basicity of a solution. It is defined as the negative logarithm of the hydrogen ion concentration: pH = -log([H3O+]).

Step 2: Recall the pH scale: A pH less than 7 indicates an acidic solution, a pH of 7 indicates a neutral solution, and a pH greater than 7 indicates a basic solution.

Step 3: Analyze the statement about basic solutions: In a basic solution, the concentration of OH- is greater than the concentration of H3O+. Therefore, the statement 'For a basic solution the concentration of H3O+ is greater than the concentration of OH-' is false.

Step 4: Consider the effect of temperature on pH: The pH of a neutral aqueous solution is 7.00 at 25°C. However, pH can vary with temperature, so the statement 'The pH of a neutral aqueous solution is 7.00 at all temperatures' is false.

Step 5: Evaluate the relationship between H3O+ and OH- concentrations: In water, the product of the concentrations of H3O+ and OH- is constant at a given temperature (Kw = [H3O+][OH-]). If the concentration of H3O+ decreases, the concentration of OH- must increase to maintain this constant, making the statement 'If the concentration of H3O+ decreases then the concentration of OH- will also decrease' false.