Analytical Chemistry: Calculate the pH.

In summary, to calculate the pH of a 5.0 x 10^-8 M HCLO4 solution, taking the negative logarithm of the concentration would yield an incorrect result. This is because the question contains a hint that the solution is a strong acid, and pH should always be below 7 for acidic solutions. Instead, the fraction of the total H+ derived from dissociation of water should be calculated, which is approximately 1.4 x 10^-9.
  • #1
whatlifeforme
219
0

Homework Statement



Calculate the pH of 5.0 x 10^-8 M HCLO4. What fraction of the total H+ in this solution is derived from dissociation of water?

Homework Equations


The Attempt at a Solution



The only thing I know to do is take -log(5.0 x 10^-8) .
 
Physics news on Phys.org
  • #2
whatlifeforme said:
The only thing I know to do is take -log(5.0 x 10^-8) .

That's not correct in this case, as it yields pH above 7, which suggests - quite nonsensically - that acid solution is slightly basic. Besides, question contains a strong hint telling you why this approach yields incorrect result.

Compare discussion here: pH of a strong acid.
 

Related to Analytical Chemistry: Calculate the pH.

1. How do I calculate pH?

The pH of a solution can be calculated using the formula pH = -log[H+], where [H+] is the concentration of hydrogen ions in moles per liter (M). Alternatively, you can use a pH meter to directly measure the pH of a solution.

2. What is the pH scale?

The pH scale is a measure of the acidity or basicity of a solution. It ranges from 0 to 14, with 0 being the most acidic, 7 being neutral, and 14 being the most basic. A change of one unit on the pH scale represents a 10-fold change in the concentration of hydrogen ions.

3. How do I determine the concentration of hydrogen ions in a solution?

The concentration of hydrogen ions can be determined using a titration method, where a known amount of a base (or acid) is added to a solution until it reaches the equivalence point. The concentration of the base (or acid) can then be used to calculate the concentration of hydrogen ions using the stoichiometry of the reaction.

4. How does pH affect chemical reactions?

pH can greatly affect the rate and direction of chemical reactions. For example, enzymes have an optimal pH at which they function most efficiently. Changes in pH can also cause changes in the ionization state of molecules, which can affect their reactivity. In addition, the pH of a solution can affect the solubility and stability of certain compounds.

5. What are some practical applications of pH in analytical chemistry?

pH is an important parameter in many analytical techniques, such as titrations, chromatography, and spectrophotometry. It is also used in various industries, such as food and beverage production, environmental monitoring, and pharmaceutical manufacturing, to ensure the quality and safety of products. Additionally, understanding pH is crucial in biological and biochemical research, as it plays a critical role in many physiological processes.

Similar threads

  • Biology and Chemistry Homework Help
Replies
1
Views
2K
  • Biology and Chemistry Homework Help
Replies
16
Views
2K
  • Biology and Chemistry Homework Help
Replies
5
Views
2K
  • Biology and Chemistry Homework Help
Replies
5
Views
2K
  • Biology and Chemistry Homework Help
Replies
4
Views
1K
  • Biology and Chemistry Homework Help
Replies
3
Views
2K
  • Biology and Chemistry Homework Help
Replies
5
Views
3K
  • Biology and Chemistry Homework Help
Replies
5
Views
3K
  • Biology and Chemistry Homework Help
Replies
2
Views
1K
Replies
8
Views
1K
Back
Top