Chemistry Chapter: Self-Ionization of Water

The self-ionisation equation of water is H₂O ↔ H⁺ + OH⁻.

At 25°C, the ionic product of water (Kw) is 1 × 10⁻¹⁴.

pH is calculated using the formula pH = -log₁₀[H⁺].

<p>The pH of that solution is approximately 6.15.</p> Signup and view all the answers

<p>A neutral solution has a pH equal to 7.</p> Signup and view all the answers

<p>pH = -log<del>10</del>[H^+^]</p> Signup and view all the answers

<p>[H^+^] = 1.995 x 10^-4^ mol/L</p> Signup and view all the answers

<p>Strong acids have large K<del>a</del> values, while weak acids have small K<del>a</del> values.</p> Signup and view all the answers

<p>Sodium hydroxide (NaOH) is a strong base because it readily accepts protons.</p> Signup and view all the answers

<p>A strong acid has a weak conjugate base, such as HCl and Cl^-.</p> Signup and view all the answers

<p>Adding OH^- shifts the equilibrium to the left, favoring the reverse reaction and resulting in Colour 1 being seen.</p> Signup and view all the answers

<p>The pH range indicates the interval over which the indicator changes color, allowing for effective monitoring of pH changes during titrations.</p> Signup and view all the answers

<p>The setup includes a burette filled with a base, a beaker containing an acid and a magnetic stir bar, and a pH sensor connected to a computer to record pH changes.</p> Signup and view all the answers

<p>Adding H^+ would react with OH^-, decreasing its concentration and shifting the equilibrium right, resulting in Colour 2 being seen.</p> Signup and view all the answers

<p>Methyl orange has a pH range of 3-5, changing from red to yellow, while phenolphthalein has a range of 8-10, changing from colorless to pink.</p> Signup and view all the answers

<p>The pH is 0.097.</p> Signup and view all the answers

<p>The pH is 13.18.</p> Signup and view all the answers

<p>The pH scale is limited to 0.1-14, only applicable at 25°C, and does not work at extremely low concentrations.</p> Signup and view all the answers

<p>You must know the dissociation constant (K<del>a</del> or K<del>b</del>) for the substance.</p> Signup and view all the answers

<p>[H^+] = \sqrt{K_a \times M_{acid}}.</p> Signup and view all the answers

<p>The pH is 2.34.</p> Signup and view all the answers

<p>An acid-base indicator changes color based on the pH of the solution.</p> Signup and view all the answers

<p>Adding H^+ ions favors the reverse reaction, resulting in Colour 1 being seen.</p> Signup and view all the answers

<p>Indicators change color at a specific pH range, signaling the endpoint of a titration. For example, methyl orange is suitable for titrating a strong acid against a weak base.</p> Signup and view all the answers

<p>A strong acid dissociates almost completely in water, resulting in a sharp increase in pH at the equivalence point of the titration.</p> Signup and view all the answers

<p>The pH rises gradually, becoming almost vertical around the equivalence point, indicating a significant change but not a sudden jump.</p> Signup and view all the answers

<p>A conjugate pair consists of an acid and its corresponding base that differ by one hydrogen ion, indicating the reversible nature of acid-base reactions.</p> Signup and view all the answers

<p>Sulfuric acid almost completely dissociates in water to produce more hydrogen ions, while a weak acid only partially dissociates.</p> Signup and view all the answers

<p>pOH = -log10[OH⁻] = -log10(0.5) ≈ 0.3, thus pH = 14 - pOH = 14 - 0.3 = 13.7.</p> Signup and view all the answers

<p>The gradual pH rise does not yield a sudden change, making it difficult to pinpoint the endpoint with common indicators.</p> Signup and view all the answers

<p>The solution turns purple as hydroxide ions remove hydrogen ions from the indicator, shifting the equilibrium.</p> Signup and view all the answers