Laborant got a task to make a buffer, which pH = 8.00. Which same concentration solutions and which ratio would you suggest him to mix?
This must be part of another series of questions since it refers to "same concentration solutions". As it stands we don't know the whole problem.
No, it's all problem. Well the end is: search all constants in internet and books
If that's all of it then your prof didn't give very good directions. I have no idea which acid he/she has in mind so I'll fly blind. I looked at the Ka values and picked HOCl.
With pH = 8 for a buffer I might pick HOCl for the acid with Ka = 3.0E-8 (you need to see what that number is in your text and use it) so pKa = 7.52.
Use the Henderson-Hasselbalch equation and solve for B/A ratio. I obtained b/a = 3.02. To prepare 1 L of buffer I would mix 5.0 mols HOCl and 15.1 mols NaOCl. You can convert to grams of each if you wish. I still think the prof had some concn in mind.If this is a biochemistry class you may want to look at the TRIS and other biochem buffers that ae used. Those (or the phosphate buffes) may be better suited for that purpose.
Thank you very much for the help! Now I see what should I do.
To suggest the Laborant the same concentration solutions and ratio to make a buffer with a pH of 8.00, we need to understand the concept of buffer solutions. A buffer solution is a solution that can resist changes in pH when small amounts of acid or base are added to it.
Typically, a buffer solution consists of a weak acid and its conjugate base or a weak base and its conjugate acid. In this case, we need to find suitable acids and bases with their conjugate forms that can give us a buffer with a pH of 8.00.
One way to achieve this is by using a weak base and its conjugate acid. Ammonia (NH3) and its conjugate acid, ammonium ion (NH4+), can be used for this purpose.
To create a buffer solution with a pH of 8.00, we need to use the Henderson-Hasselbalch equation:
pH = pKa + log([A-]/[HA])
Where pH is the desired pH of 8.00 and pKa is the negative logarithm of the acid dissociation constant for the weak acid used. In this case, we are using the conjugate acid NH4+ with a pKa of 9.25.
To calculate the ratio of [A-] to [HA], we can rearrange the Henderson-Hasselbalch equation:
[A-]/[HA] = 10^(pH - pKa)
Substituting the values, we get:
[A-]/[HA] = 10^(8.00 - 9.25)
[A-]/[HA] = 10^-1.25
From this equation, we conclude that the ratio of [A-] to [HA] should be 0.0562.
Therefore, to create the desired buffer solution with a pH of 8.00, the Laborant should mix 0.0562 parts of ammonia (NH3) with its conjugate acid, ammonium ion (NH4+), in the same concentration.
It is important to note that the exact concentrations and volumes of the solutions used will depend on the desired volume of the buffer solution and the specific molarities of the chemicals used. The values calculated here serve as a general guideline.