How Do You Calculate the pH of a Sodium Ethanoate Solution?

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SUMMARY

The discussion focuses on calculating the pH of a sodium ethanoate solution using the given pKa of ethanoic acid, which is 4.75. The user, Joe, correctly identifies the need to derive the acid dissociation constant (Ka) from the pKa value and applies it to a 5 x 10^-2 mol/dm³ sodium ethanoate solution. However, the response highlights that Joe's reasoning lacks clarity regarding the concentrations involved in the dissociation process. The conversation emphasizes the importance of accurately representing the chemical species and their concentrations in pH calculations.

PREREQUISITES
  • Understanding of acid-base chemistry, specifically pKa and Ka values.
  • Familiarity with the dissociation of weak acids and their conjugate bases.
  • Knowledge of pH calculation methods and equations.
  • Experience with chemical concentration units, particularly mol/dm³.
NEXT STEPS
  • Study the relationship between pKa and Ka in detail.
  • Learn how to calculate pH for buffer solutions involving weak acids and their salts.
  • Explore the use of chemical calculators like BATE for pH calculations.
  • Investigate the impact of concentration changes on pH in weak acid-strong base titrations.
USEFUL FOR

Chemistry students, laboratory technicians, and educators involved in teaching acid-base equilibria and pH calculations will benefit from this discussion.

josephcollins
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Hi ppl. I have a question. I'm given the pka of ethanoic acid/ethanoate ions at 4.75 and i have to work out the ph of a 5*10^-2 moldm3 solution of sodium ethanoate. I worked it out by getting the Ka from 10^-4.75 and then saying that the concentration of Ch3COO- in the dissociation of ethanoic acid is also 5*10^-2 moldm3. Then i used the equation for the Ka to get the corresponding concentration of H+ ions in this dissociation and hence the ph, is this method of reasoning correct? Thanks, Joe
 
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The question itself seems to indicate an initial concentration of ethanoate, however, your discussion implies ethanoic acid? Please be more clear...
 

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