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Titration instructions for the determination of titratable acidity

1. - Deliver the 0.1M NaOH from the burette at a steady rate slowing the delivery once approximately 5 ml has been delivered or the pH meter reaches a pH of 5.0. (see diagram)

2. - Continue slowly adding NaOH, adding one drop at a time when nearing the end point, until one drop produces a permanent pink coloration or a pH of 8.35 is reached.

• Some experience is required when performing weak acid, strong base titrations, using indicators to detect the end point.(see explanation).
  
  
• When using a pH meter the increase in pH is exponential and will zip through from pH 7 to pH 8. Hence slow up.
  
  
• If you over shoot the mark, record the amount of NaOH and slow up before this volume or pH is reached on subsequent titrations.
  
  
• If using the phenolphthatalein indicator solution, the pink coloration will appear at the site of addition and then disappear as the NaOH is dispersed.
  
  The increasing persistence of the pink coloration indicates the approaching end point.
  
  The pink coloration can be detected more clearly if a white background (e.g. white paper) is utilized.
  
  
• When analyzing red wines, the red colour and the pH changes affecting red wine colour makes detecting the end point problematic, requiring some experience.
  
  Hence utilising a pH meter to detect the end point is recommended with red wines.
  
  
• To increase accuracy and check for precision and good technique, three (3) titrations should be performed and the average titre used for calculations
  
  
  

• SO₂ Titation instructions
  
  
• Acid titation instructions
  
  
• Primary and secondary standards
  
  
• Titre
  
  
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