Create Science Lab Procedure Guide

# Laboratory Procedure Guide: Acid-Base Titration to Determine Unknown Concentration ## EXPERIMENT OVERVIEW **Purpose:** Determine the molarity of an unknown HCl solution using standardized NaOH through titration techniques. **Duration:** 90 minutes **Skill Level:** Intermediate **Learning Objectives:** Students will master volumetric analysis, indicator selection, and precision measurement techniques. ## SAFETY REQUIREMENTS **PPE Required:** Safety goggles, lab coat, closed-toe shoes, nitrile gloves **Hazards:** Corrosive acids and bases; potential for chemical burns and eye injury **Emergency:** Eyewash station located at station 3; safety shower near exit **Waste Disposal:** Neutralize solutions to pH 6-8 before disposal in designated container ## MATERIALS AND EQUIPMENT - 50 mL buret (±0.1 mL accuracy) - 250 mL Erlenmeyer flasks (3) - 10 mL graduated pipet - Standardized 0.1000 M NaOH solution - Unknown HCl solution - Phenolphthalein indicator - Distilled water - Buret clamp and ring stand ## STEP-BY-STEP PROCEDURE 1. Rinse buret twice with 5 mL portions of NaOH solution 2. Fill buret with standardized NaOH, ensuring no air bubbles 3. Record initial buret reading to nearest 0.01 mL 4. Pipet exactly 10.00 mL unknown HCl into Erlenmeyer flask 5. Add 2-3 drops phenolphthalein indicator 6. Titrate slowly until persistent pale pink endpoint (30 seconds) 7. Record final buret reading 8. Repeat trials until three concordant results (±0.1 mL) **Expected Results:** Titration volumes should fall between 8-12 mL for typical unknowns.