## 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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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 pHWhat is the pH of a solution with a hydrogen-ion concentration of 4.2 × 10–10M? (contd.) 3 Sample problem: Calculating pHCalculate the pH of a solution with a hydroxide concentration of 1.2 × 10–3M. 4 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 pOHKw = 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 pHCalculate the pH of a solution with a pOH of 12. 8 9 Sample problem: Calculating pHCalculate the pOH of a solution with a pH of 9. 9 10 Sample problem: Calculating pHCalculate the hydrogen ion concentration of a solution with a pH of 8.5.

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10 11 Sample problem: Calculating pHCalculate the hydrogen ion concentration of a solution with a pOH of 13.5. 11 