[6] Measuring and Calculating pH

In this video, we move from theory to practice by exploring how to measure and calculate pH in a real-world laboratory setting. We demonstrate the essential tools every chemist needs and walk through the complex, multi-step math required to find pH when you are only given the hydroxide ion concentration [OH⁻]. Key Topics Covered: Lab Instrumentation: How to use and maintain a pH meter, including the care of the sensitive glass probe and its storage in potassium chloride salt solutions. Visual Indicators: A look at litmus paper, universal pH strips, and the science behind "at-home" indicators like purple cabbage juice. The Hydroxide Calculation: A step-by-step guide to avoiding the common mistake of calculating pH directly from the base concentration. Learn to use the 10⁻¹⁴ constant to find [H⁺] first. Working Backward: How to determine both hydrogen and hydroxide concentrations starting only from a known pH value (e.g., pH 3). Practice Walkthroughs: Detailed examples showing how to categorize a solution as acidic or basic based on your final calculated values.