## Presentation on theme: "How is pH defined? The pH of a solution is the negative logarithm of the hydrogen-ion concentration. The pH may be represented mathematically, using the."— Presentation transcript:

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Negative logarithm of the hydrogen ion concentration 1 How is pH defined? The pH of a solution is the negative logarithm of the hydrogen-ion concentration. The pH may be represented mathematically, using the following equation: pH = –log In pure water or a neutral solution, = 1 × 10–7M, and the pH is 7. pH = –log(1 × 10–7) = –(log 1 × log 10–7) = –(0.0 + (–7.0)) = 7.0 If the of a solution is greater than 1 × 10–7M, the pH is less than 7.0. If the of the solution is less than 1 × 10–7M, the pH is greater than 7.0.

In pure water or a neutral solution,

= 1 × 10–7M, and the pH is 7. pH = –log(1 × 10–7) = –(log 1 × log 10–7) = –(0.0 + (–7.0)) = 7.0. If the of a solution is greater than 1 × 10–7M, the pH is less than 7.0. If the of the solution is less than 1 × 10–7M, the pH is greater than 7.0."> 2 **Sample problem: Calculating pH**What is the pH of a solution with a hydrogen-ion concentration of 4.2 × 10–10M? (contd.)

3 **Sample problem: Calculating pH**Calculate the pH of a solution with a hydroxide concentration of 1.2 × 10–3M.

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5 **How are and related in an aqueous solution?**The reaction in which water molecules produce ions is called the self-ionization of water. This reaction can be written as a simple dissociation. H2O(l) ⇄ H+(aq) + OH–(aq) The self-ionization of water occurs to a very small extent. In pure water at 25°C, the concentration of hydrogen ions is only 1 × 10–7M. The concentration of OH– is also 1 × 10–7M because the numbers of H+ and OH– ions are equal in pure water. Any aqueous solution in which and are equal is a neutral solution.

and related in an aqueous solution" title="The reaction in which water molecules produce ions is called the self-ionization of water. This reaction can be written as a simple dissociation. H2O(l) ⇄ H+(aq) + OH–(aq) The self-ionization of water occurs to a very small extent. In pure water at 25°C, the concentration of hydrogen ions is only 1 × 10–7M. The concentration of OH– is also 1 × 10–7M because the numbers of H+ and OH– ions are equal in pure water. Any aqueous solution in which and are equal is a neutral solution."> 6 For aqueous solutions, the product of the hydrogen-ion concentration and the hydroxide-ion concentration equals 1.0 10–14. = 1.0 10–14 This equation is true for all dilute aqueous solutions at 25°C. The product of the concentrations of the hydrogen ions and the hydroxide ions in water is called the ion-product constant for water (Kw). Kw = × = 1.0 × 10–14 A solution in which is greater than is an acidic solution. In acidic solutions, the is greater than 1 × 10–7M. A basic solution is one in which is less than . The of a basic solution is less than 1 × 10–7M. Basic solutions are also known as alkaline solutions.

= 1.0 10–14. This equation is true for all dilute aqueous solutions at 25°C. The product of the concentrations of the hydrogen ions and the hydroxide ions in water is called the ion-product constant for water (Kw). Kw = × = 1.0 × 10–14. A solution in which is greater than is an acidic solution. In acidic solutions, the is greater than 1 × 10–7M. A basic solution is one in which is less than . The of a basic solution is less than 1 × 10–7M. Basic solutions are also known as alkaline solutions."> 7 **You can use this equation to convert between pH and pOH**Kw = pH + pOH Kw always equals 14 So.. pH + pOH = 14 You can use this equation to convert between pH and pOH 7

8 **Sample problem: Calculating pH**Calculate the pH of a solution with a pOH of 12. 8

9 **Sample problem: Calculating pH**Calculate the pOH of a solution with a pH of 9. 9

10 **Sample problem: Calculating pH**Calculate the hydrogen ion concentration of a solution with a pH of 8.5.

See more: Which Of The Following Explains The Slope Of The Aggregate Demand Curve ?

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11 **Sample problem: Calculating pH**Calculate the hydrogen ion concentration of a solution with a pOH of 13.5. 11