Can the ph of a buffer solution of potassium hydroxide decrease when exposed to air overnight?
I'm pretty sure the answer is yes
no im wrong, the ph will not decrease.
I wouldn't think so if it is a good buffer solution. The pH of good buffer solutions don't change unless their buffering capacity is exceeded.
Yes, the pH of a buffer solution of potassium hydroxide can decrease when exposed to air overnight. Potassium hydroxide is a strong base, and when it reacts with carbon dioxide in the air, it forms potassium carbonate. This reaction reduces the concentration of hydroxide ions (OH^-) in the solution and increases the concentration of carbonate ions (CO3^2-). Since carbonate ions are less basic than hydroxide ions, the pH of the solution will decrease.
To calculate the exact change in pH, you can use the Henderson-Hasselbalch equation, which is commonly used to determine the pH of a buffer solution:
pH = pKa + log([A^-]/[HA])
Where:
- pH is the measure of hydrogen ion concentration (a measure of acidity or alkalinity).
- pKa is the negative logarithm of the acid dissociation constant (a measure of the strength of the acid).
- [A^-] is the concentration of the ionized form of the acid.
- [HA] is the concentration of the non-ionized form of the acid.
In the case of a solution of potassium hydroxide, the hydroxide ions act as the base (A^-) and there is no non-ionized form (HA) since potassium hydroxide is a strong base. Therefore, the concentration of [A^-] can be directly related to the concentration of hydroxide ions.
By calculating the pH before and after exposure to air, you can determine whether the pH decreases or not.
Keep in mind that other factors such as temperature, concentration, and presence of other ions in the solution can also affect the pH.