Why ignore the rough titre? A10: It is not accurate enough (overshoot possible) Final Answer for Level 2 (to submit or memorize) The concentration of the unknown hydrochloric acid is 0.0985 mol/dm³.

Concentration of unknown HCl? A9: 0.0985 mol/dm³

What is the volume of HCl pipetted each time? A2: 25.00 cm³

What color change signals the endpoint? A4: Colorless to permanent pale pink

Moles of NaOH in mean titre? A7: 0.002462 mol

Calculate the mean titre from: 24.60, 24.60, 24.65 cm³ A6: 24.62 cm³

What indicator is used? A3: Phenolphthalein