Where Did I Go Wrong in Calculating Hydroxide Ion Concentration?

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SUMMARY

The discussion centers on calculating the hydroxide ion concentration in a carbonic acid (H2CO3) solution, specifically at 25°C with a concentration of 4x10-4M. The participant initially calculated the pH as 4.3979, leading to a pOH of 10.602, which did not match the expected answer. The key error identified was the need for clarity in stating the question and ensuring proper rounding of significant figures in the results.

PREREQUISITES
  • Understanding of pH and pOH calculations
  • Familiarity with the dissociation of carbonic acid (H2CO3)
  • Knowledge of significant figures in scientific calculations
  • Basic principles of aqueous solutions and ion concentrations
NEXT STEPS
  • Review the calculation of pH and pOH in aqueous solutions
  • Study the dissociation constants of carbonic acid (H2CO3)
  • Learn about significant figures and their importance in scientific reporting
  • Explore common mistakes in acid-base chemistry calculations
USEFUL FOR

Chemistry students, educators, and anyone involved in acid-base chemistry calculations will benefit from this discussion.

harambe
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Homework Statement


The hydroxide ion concentration in an aques H2CO3 solution is 4X10^{-4}M at 25°C OH- ion concentration in the solution is

Homework Equations



Ph=log(H+ or OH-) [/B]

The Attempt at a Solution



I calculated the PH of H+ in the solution which came to be 4.3979.Considering this to be water solution , I get POH to be 10.602..This doesn't match answer. Where did I go wrong[/B]
 
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harambe said:
which came to be 4.3979

Check your math.

Note: you are showing way too many figures in your results. 4.4 would do here (and would be exactly as wrong as what you wrote).
 
Don't forget to tell us what the question is. Given the concentration of hydroxide ion calculate the OH- concentration is the easiest question I've seen here yet.
 
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epenguin said:
Don't forget to tell us what the question is. Given the concentration of hydroxide ion calculate the OH- concentration is the easiest question I've seen here yet.
Who is the George Washington bridge named after?
 
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Chestermiller said:
Who is the George Washington bridge named after?

GW?
 

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