Flashcards in 17.3.2 CIA Demonstration: Barium Hydroxide-Sulfuric Acid Titration Deck (2)
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1
Q
CIA Demonstration: Barium Hydroxide-Sulfuric Acid Titration
A
- In a titration of a monoprotic acid there are exactly the same number of moles of base as there are moles of acid at the equivalence point.
- The demonstration uses a conductometric technique where the conductivity of the solution is monitored to establish the endpoint of the titration.
2
Q
note
A
- In an acid-base titration, an acid is neutralized with a base.
- A strong base is added to a sample of acid until the
equivalence point is reached. - In a titration of a monoprotic acid there are exactly the same number of moles of base as there are moles of acid at the equivalence point.
- The visual indication that the solution is at the equivalence point is usually made using an indicator such as phenolphthalein, which changes color from colorless to pink at a pH of approximately seven.
- The demonstration uses a conductometric technique where the conductivity of the solution is monitored to establish the endpoint of the titration.
- There are two reactions that take place in the barium
hydroxide (Ba(OH) 2 )-sulfuric acid (H 2 SO 4 ) titration. The Ba 2+ ion reacts with the SO 42– ion to form barium sulfate (BaSO 4 ) and the OH – ion from the barium hydroxide reacts with the H + ion from the sulfuric acid to form water (H 2 O). - The solubility product (K sp ) of barium sulfate is small (1.08 x 10 –10 at 25°C). The auto-ionization of water also does not give rise to appreciable concentrations of protons or hydroxide ion (K w = 1.0 x 10 –14 at 25°C). Neither of these molecules contributes ions to a solution.
- At the equivalence point there will be no ions in solution to act as conductors, the circuit will be broken and the lamp will go out.
- Past the equivalence point, the sulfuric acid will dissociate, the solution will again be conductive, and the lamp will relight.