Determining the phosphoric acid content in soft drinks
Answers
Phosphoric acid (H₃PO₄) is a weak acid that is known to be present in higher concentrations than other acids in carbonated drinks.
The concentration of phosphoric acid in soft drinks can be measured by a simple acid-base titration. The sample of the soft drink can be titrated against Sodium hydroxide solution to determine the concentration of phosphoric acid. The following reaction will occur.
H₃PO₄ (aq) + OH⁻ (aq) → H₂O (l) + H₂PO₄⁻ (aq)
As it is being titrated a pH sensor detects the change in pH. The region with rapid pH change will be considered as the equivalence point.
The volume of NaOH that is used as the titrant at the equivalence point will be used to calculate the molarity of phosphoric acid.
Answer:
Different carbonated beverages have different methods for determining the content of phosphonic acid. Take Coca-Cola as an example:
1.Pour a bottle of Coca-Cola into the round bottom flask and stir for 2-3 minutes. Add 6.0 g of activated carbon. Heated at reflux for ten minutes.
2.Remove the heating pack and replace with an ice water bath. After the sample was cooled to 20 °C, the mixture was filtered with double-thick filter paper. The filtrate should be filtered several times.
3.Titration: A prepared Coca-Cola sample was titrated with a sodium hydroxide solution using a pH meter.
4.Adjustment of the pH meter: Calibrate the pH meter with two buffer solutions.
Determination of content
1.Draw the titration curve and determine the first equivalence point.
2.Measure the pH value and the pH value of the first equivalence point of the Coca-Cola beverage after heating and cooling to 20℃.
3.Calculate the concentration of phosphoric acid in Coca-Cola.
Phosphoric acid is harmful to bone because phosphoric acid has an adverse effect on calcium metabolism and bone quality. For good health, try to drink less carbonated beverages.
Explanation: