Tonicity and Osmoticity of saline with weak acid

  • Thread starter uzi kiko
  • Start date
  • Tags
    Acid Weak
In summary, the conversation discusses the tonicity and osmoticity of a solution containing cells and a weak acid with a pK of 7.0 and a concentration of 50mM, where the PH is 4. The solution is found to be isotonic and hyperosmotic due to the weak acid remaining in almost the same concentration. The equation log([A-]/[HA]) = PH - pKa is used to calculate this. The conversation also mentions that only the uncharged fraction of the drug can diffuse across membranes.
  • #1
uzi kiko
22
3
Hi all

I got an exercise:
Cells were floated in a mass in a solution with 150mM of NaCl (isotonic conditions). A weak acid was added to the solution with a pK of 7.0 and concentration of 50mM in the solution.
What is the tonicity and osmoticity of the new solution if PH=4

I know that I should use the following equation:
log([A-]/[HA]) = PH - pKa

But It seem that I am getting the wrong result.
Can somebody help?
 
Physics news on Phys.org
  • #2
Thread moved to the homework forums. No template.
 
  • #3
The answer in case somebody else will interest:

Need to understand that only the fraction of the drug that is uncharged can diffuse across membranes.
So in case PH=4 and pKa=7 the solution will be acidic so the weak acid remain almost in the same concentration (50mM)

so the solution is isotonic and hyperosmotic
 

Related to Tonicity and Osmoticity of saline with weak acid

1. What is the difference between tonicity and osmoticity?

Tonicity refers to the ability of a solution to cause water to move across a semipermeable membrane, while osmoticity refers to the number of particles in a solution that contribute to its osmotic pressure. In other words, tonicity is a measure of the concentration of solutes that can affect cell volume, while osmoticity is a measure of the total concentration of all solutes in a solution.

2. How does a weak acid affect the tonicity and osmoticity of saline?

A weak acid, such as acetic acid, will dissociate partially in water to form both hydrogen ions (H+) and acetate ions (CH3COO-). These ions will contribute to the overall tonicity of the solution, as they can affect cell volume by attracting or repelling water. However, the weak acid will not contribute significantly to osmoticity because it does not fully dissociate and therefore does not add to the total number of particles in the solution.

3. Can the tonicity and osmoticity of saline with weak acid be altered?

Yes, the tonicity and osmoticity of saline with weak acid can be altered by changing the concentration of the weak acid. Increasing the concentration of the weak acid will increase the tonicity of the solution, while the osmoticity will remain relatively unchanged as the total number of particles in the solution does not significantly increase.

4. How does the tonicity and osmoticity of saline with weak acid affect cellular function?

The tonicity of a solution can have a significant impact on cellular function. If the tonicity is too high, it can cause cells to shrink or burst, leading to cell damage or death. On the other hand, if the tonicity is too low, it can cause cells to swell and potentially burst as well. Osmoticity, on the other hand, does not directly affect cellular function but can indirectly impact it by altering the concentration of solutes and ions inside the cell.

5. Are there any potential risks associated with using saline with weak acid in medical procedures?

There are potential risks associated with using saline with weak acid in medical procedures. If the concentration of the weak acid is too high, it can cause damage to cells and tissues. Additionally, if the pH of the solution is not carefully regulated, it can lead to acid-base imbalances in the body. It is important for medical professionals to carefully monitor the concentration and pH of saline with weak acid to avoid these potential risks.

Similar threads

Chemistry Moles of NaOH to Create Buffer Solution pH=6 in 0.42M Ethanoic Acid
    • Biology and Chemistry Homework Help
Replies
3
Views
2K
Calculating pKa from pH: Understanding Titration
    • Biology and Chemistry Homework Help
Replies
3
Views
2K
Henderson Hasselbalch Equation - Request for Clarification
    • Chemistry
Replies
8
Views
961
Chemistry Solving pH Changes: Adding Acid to a Buffer or Water
    • Biology and Chemistry Homework Help
Replies
16
Views
2K
Titration of acetic acid w/ NaOH problem
    • Biology and Chemistry Homework Help
Replies
2
Views
2K
Max Buffering Capacity w/ 0.6 mol HAc & NaOH
    • Biology and Chemistry Homework Help
Replies
23
Views
2K
(Chemistry) Ka of unknown acid by titrations.
    • Biology and Chemistry Homework Help
Replies
1
Views
3K
Question about acid and base indicators
    • Biology and Chemistry Homework Help
Replies
7
Views
6K
Titration of Sulfurous Acid: Calculating pH with Ka Values
    • Biology and Chemistry Homework Help
Replies
3
Views
2K
Calculating the pH of a Buffer Solution
    • Biology and Chemistry Homework Help
Replies
7
Views
3K

Hot Threads

Recent Insights

Back
Top