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The first 4 trials will be the titration between these acid/base pairs. For each dispense 25.0 mL of acid into 250-ml Erlenmeyer flask and titrate with base (in burette). Experiment 1: 3.0 M HNO3/1.0 M NaOH (phenolphthalein indicator) Experiment 2: 3.0 M HCV/1.0 M NH3 (methyl orange indicator) Experiment 3: 1.0 M HCV/0.50 M Mg(OH)₂ (methyl orange indicator) Experiment 4: 1.0 M H₂SO4/3.0 M NaOH (phenolphthalein indicator) The 5th experiment is one of your own choosing, (pick an acid/base pair that you have not used yet). Record your data below. DATA TABLE: Experimen Volume Acid in Flask t 1 2 3 4 5 CALCULATIONS: Experimen Moles of Acid in Flask t 1 2 3 4 5 Concentration of Acid (M) Moles of Base Dispensed Volume Base Dispensed Molarity of Base (calculate and check)

1. Determine the moles of acid in the flask for all 5 experiments. (Hint: You know the volume and molarity) 2. Write the balanced equation between acid and base for all 5 experiments 3. Determine the moles of base dispensed from the stoichiometric ratio from the balanced equation. 4. Determine the molarity of the base solution. (Hint: Use the volume of base dispensed)

POST LAB QUESTIONS: 1) During a titration, 28.53 mL of a 0.15 M solution of barium hydroxide is used to neutralize 20.00 mL of a phosphoric acid solution of an unknown concentration. What is the concentration of the phosphoric acid solution? 2) Explain why a "pale pink" solution is desired when titrating and why you do not want the solution to be bright pink. How would the molarity of the base be affected (too high or too low) if the solution is too pink?