Understanding Zn(OH)2 & Al(OH)3: Ampiprotic Properties

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SUMMARY

Zn(OH)2 and Al(OH)3 are identified as amphiprotic substances due to their ability to act both as acids and bases. When reacted with 6M HCl, they demonstrate acidic behavior by increasing H+ ions, resulting in a colorless solution with Phenolphthalein. Conversely, when reacted with 6M NaOH, they exhibit basic properties, turning red in the presence of Phenolphthalein. The presence of precipitates during these reactions further supports their amphiprotic nature.

PREREQUISITES
  • Understanding of amphiprotic substances
  • Knowledge of acid-base reactions
  • Familiarity with Phenolphthalein as a pH indicator
  • Basic principles of chemical precipitation
NEXT STEPS
  • Research the amphiprotic properties of other hydroxides, such as Pb(OH)2
  • Study the role of Phenolphthalein in acid-base titrations
  • Explore the concept of chemical precipitation in more detail
  • Investigate the behavior of Zn(OH)2 and Al(OH)3 in different pH environments
USEFUL FOR

Chemistry students, educators, and researchers interested in acid-base chemistry and the properties of amphiprotic substances.

Epsillon
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Homework Statement



basically why are Zn(OH)2 and Al(OH)3 ampiprotic given that they give have a clear color when reacted with water and Phenolphthalein and given that when reacted with 6M HCl they are clear and when reacted with 6M of NaOH they are red.

Note for Phenolphthalein red mean basic colourless means acidic.



The Attempt at a Solution


I get that they react as an acid when in water but to prove that they are ampiprotic you have to prove they react as a base with HCl which I cannot figure out how to do since they can also react as an acid with HCl increasing H+ ions still giving you coloirless color.
 
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Your experimental setup didn't allow to conlcude anything about Al and Zn amphoterism.
 
Oh i think i have to use the fact that there were precipitates
 

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