Solubility and Titration
Not what you're looking for?
(See attached file for full problem description)
---
1. Tooth enamel consists of hydroxyapatite, Ca5(PO4)3OH (Ksp = 6.8x10-37). Fluoride ion added to drinking water reacts with Ca5(PO4)3OH to form the more tooth decay-resistant fluorapatite, Ca5(PO4)3F (Ksp =1.0x10-60). Fluoridated water has dramatically decreased cavities among children. Calculate the solubility of Ca5(PO4)3OH and of Ca5(PO4)3F in water.
2. A 35.00 mL solution of .2500 M HF is titrated with a standardized .1532 M solution of NaOH at 25◦C.
(a) What is the pH of the HF solution before titrant is added?
(b) How many milliliters of titrant are required to reach the equivalence point?
(c) What is the pH at .50 mL before the equivalence point?
(d) What is the pH at the equivalence point?
(e) What is the pH at .50 mL after the equivalence point?
---
Purchase this Solution
Solution Summary
This solution involves solving for solubility of compounds in water and various pH questions about titration.
Solution Preview
Please refer to the attached file. Cheers.
1. Tooth enamel consists of hydroxyapatite, Ca5(PO4)3OH (Ksp = 6.8×10-37). Fluoride ion added to drinking water reacts w/Ca5(PO4)3OH to form the more tooth decay-resistant fluorapatite, Ca5(PO4)3F (Ksp =1.0×10-60). Fluoridated water has dramatically decreased cavities among children. Calculate the solubility of Ca5(PO4)3OH and of Ca5(PO4)3F in water.
Solution:
The balanced equation is:
Ca5(PO4)3OH(s) 5 Ca2-(aq) + 3 PO43-(aq) + OH-(aq)
So, the Ksp expression will be:
Ca5(PO4)3OH 5 Ca2- + 3 PO43- + OH-
5x 3x x
The solubility of Ca5(PO4)3OH is 2.72 × 10-5 M.
The balanced equation is:
Ca5(PO4)3F(s) 5 Ca2-(aq) + 3 PO43-(aq) + F-(aq)
So, the Ksp expression will be:
Ca5(PO4)3OH 5 Ca2- + 3 PO43- + F-
5x 3x x
The solubility of Ca5(PO4)3F is 6.11 × 10-8 M.
2. A 35.00 mL solution of .2500 M HF is titrated with a standardized .1532 M solution of NaOH at 25◦C.
(a) What is the pH of the HF solution before titrant is added?
(b) How ...
Purchase this Solution
Free BrainMass Quizzes
Thermochemistry
The quiz helps in revising basic concepts about thermochemistry.
Functional groups in Organic Chemistry
You will be tested on the names of functional groups in Organic Chemistry. It is very important to know the functional groups to understand Organic reactions.
Organic Chemistry Naming: Alkanes
This is a quiz which is designed to assist students with learning the nomenclature used to identify organic compounds. This quiz focuses on the organic compounds called Alkanes.
Match Elements with their Symbols
Elements are provided: choose the matching one- or two-letter symbol for each element.