What is the Correct Value of Kw at 10°C?

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SUMMARY

At 10°C, the correct value of the ion product of water, Kw, is approximately 3 x 10^-15, contrary to the commonly referenced value of 1 x 10^-14 at 25°C. The discussion highlights the confusion surrounding the dissociation of HCl in water and its impact on hydroxide ion concentration. The equilibrium constant Kw is defined as the product of the concentrations of hydrogen ions [H+] and hydroxide ions [OH-]. Understanding the temperature dependence of Kw is crucial for accurate calculations in aqueous solutions.

PREREQUISITES
  • Understanding of acid-base chemistry, specifically the dissociation of strong acids like HCl.
  • Familiarity with the concept of equilibrium constants, particularly Kw.
  • Knowledge of temperature effects on chemical equilibria.
  • Basic proficiency in logarithmic calculations and scientific notation.
NEXT STEPS
  • Research the temperature dependence of Kw and its implications for acid-base chemistry.
  • Learn about the dissociation constants (Ka and Kb) for various acids and bases.
  • Explore the relationship between pH, pOH, and ion concentrations in different temperatures.
  • Study the role of temperature in chemical equilibria and its effect on reaction rates.
USEFUL FOR

Chemistry students, educators, and anyone preparing for standardized tests like the MCAT who seeks a deeper understanding of acid-base equilibria and temperature effects on chemical properties.

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Homework Statement


At 10 C, the concentration of OH in 1 M of HCl is approximately:

Answer: 3x10^15

Homework Equations


Kw=KaKb

The Attempt at a Solution


This answer throws me off. If we assume that HCl completely dissociates, we use the [H+] from the acid in the above equation:
1x10^-14 = 1 [OH]

I get 1 x 10^-14, not 3 x 10^-15. What am I missing here? Is my book wrong? Thanks.
 
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Thanks for the table but I still don't think I get it. Since this is for the mcat, how am I supposed to calculate the OH concentration at 10 C?
 
What is the definition of Kw?
 
Kw is the equilibrium constant for [H+] and [OH-]. In aqueous solution, Kw remains at 10^-14.
 
brake4country said:
In aqueous solution, Kw remains at 10^-14.

Have you really seen the table? What is the Kw value at 10°C?
 

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