This year's AP exam is done on May 1st. Hope all my students did well. The results will be out at the beginning of July. As always, I am less busy and will continue with my blog.
Here is the 66th question of my series.
66. The ionization process of water is endothermic with Kw=1.0e-14 at 25 degrees Celsius. What is the pOH of a solution that has a pH of 2 at 50 degrees Celsius?
A. greater than 12
B. Less than 12
C. equal to 12
D. can not be determined
The Kw of water is a special case Keq which represents the Keq of the self ionization process of water. All the properties of Keq apply to Kw. Since it is an equilibrium constant, it only depends on temperature. Since the process is endothermic, Kw will increase as temperature increases. As a result, at 50 degrees Celsius, Kw will be less than 1.0e-14. In neutral water, the concentration of hydronium ion and hydroxide ion are always equal, pH=pOH and the. sum of pH and pOH is always pKw. pKw at 25 degree Celsius is 14. At 50 degrees Celsius, both ion concentration will be less than 1.0e-7. the total of pH and pOH will be less than 14. if pH is 2, then pOH will be less than 12.
B is the correct answer.
Thank you for visiting my blog. If you have any questions, please do not hesitate to contact me at vancouverchemistrytutor@gmail.com
No comments:
Post a Comment