Determining pH when given volume and concentration of a solution?

In summary: It's usually called Tris-HCl. It's probably important that you know that the pKa is 8.1 and that it's a zwitterion.In summary, the conversation discusses two problems related to determining the pH of a Tris solution in acid form. The equations used are the Hendersen-Hasselbalch equation and the pKa formula. The question is raised about whether the addition of NaOH to the solution affects the choice of equation. The clarification is given that Tris can exist in acid form as Tris-HCl, with a pKa of 8.1, and is a zwitterion.
  • #1
Violagirl
114
0

Homework Statement



I'm stuck on these two problems:

A) IF you make a 50 mL of a 0.1 M Tris solution (in acid form), what will be the pH?

B) If you add 2 mL of 1 M NaOH to the above solution, what will be the pH?

Homework Equations



pH = pka + log [A/HA] Hendersen-Hasselbalch

The Attempt at a Solution



I'm not sure if HH is the right equation to use or not for this one when given both volume and concentration or if you add the NaOH to it. Help is greatly appreciated.
 
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  • #2
Violagirl said:

Homework Statement



I'm stuck on these two problems:

A) IF you make a 50 mL of a 0.1 M Tris solution (in acid form), what will be the pH?

B) If you add 2 mL of 1 M NaOH to the above solution, what will be the pH?

Homework Equations



pH = pka + log [A/HA] Hendersen-Hasselbalch

The Attempt at a Solution



I'm not sure if HH is the right equation to use or not for this one when given both volume and concentration or if you add the NaOH to it. Help is greatly appreciated.

It would help if you could define what "Tris solution (in acid form)" is.
 
  • #3
I'm not sure, that is the exact way that the question was asked...Is it referring to a Tris buffer of a 100% solution?
 
  • #4
I can only repeat after Pranav-Arora - what does it mean "Tris in acid form"? What other forms can Tris have?
 
  • #5
This might help you...
160px-Tris.png

http://en.wikipedia.org/wiki/Tris
 
Last edited:
  • #6
You can buy tris which they call tris base (HOCH2)3CNH2, and you can buy tris hydrochloride (crystalline) (HOCH2)3CNH3+Cl-, I think the latter is what they must mean.
 

FAQ: Determining pH when given volume and concentration of a solution?

How do I calculate the pH of a solution when I am given its volume and concentration?

To calculate the pH of a solution, you will need to use the formula pH = -log[H+], where [H+] represents the concentration of hydrogen ions in moles per liter. You can find the concentration by dividing the number of moles of solute by the volume of the solution in liters.

What is the difference between concentration and volume in determining pH?

Concentration refers to the amount of solute present in a given volume of solution, while volume is simply the amount of space that the solution occupies. In the context of determining pH, concentration is used to calculate the concentration of hydrogen ions, which is used in the pH formula.

Can I use any units for volume and concentration when determining pH?

It is important to use consistent units when calculating pH. Volume should be in liters and concentration should be in moles per liter. If you are given other units, you will need to convert them accordingly before using them in the pH formula.

How does the pH of a solution change as its concentration or volume changes?

The pH of a solution is directly affected by the concentration of hydrogen ions present. As the concentration increases, the pH will decrease (become more acidic). Similarly, as the volume of the solution increases, the concentration of hydrogen ions will decrease, causing the pH to increase (become more basic).

Why is it important to know the pH of a solution?

The pH of a solution is a measure of its acidity or basicity, which has important implications in various fields such as chemistry, biology, and environmental science. Some chemical reactions only occur under certain pH conditions, and in biological systems, pH plays a crucial role in maintaining homeostasis. Additionally, the pH of a solution can affect the properties and behavior of substances dissolved in it.

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