Calculate the pH of a buffer solution containing 1.0 mol/dm3 CH3COONa
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To calculate the pH of a buffer solution, you need to know the concentration of the acidic component (CH3COOH) and the concentration of the salt formed by its conjugate base (CH3COONa). In this case, you have the concentration of CH3COONa, which is 1.0 mol/dm^3, but you need the concentration of CH3COOH.
To find the concentration of CH3COOH, you need to know the pKa of acetic acid (CH3COOH). The pKa value represents the acidity of an acid and can be found in reference books or online sources. The pKa for acetic acid is approximately 4.76.
Using the Henderson-Hasselbalch equation, the pH of a buffer solution can be calculated as follows:
pH = pKa + log([CH3COONa]/[CH3COOH])
Given that the concentration of CH3COONa is 1.0 mol/dm^3 and the pKa is 4.76, you need to find the concentration of CH3COOH to calculate the pH.
Assuming that the initial concentration of CH3COOH is X mol/dm^3, the concentration of CH3COONa and CH3COOH in the buffer solution can be expressed as [CH3COONa] = 1.0 mol/dm^3 and [CH3COOH] = X mol/dm^3, respectively.
Substituting these values in the Henderson-Hasselbalch equation, we get:
pH = 4.76 + log(1.0/X)
To solve for X, we need to rearrange the equation:
log(1.0/X) = pH - 4.76
Now, we can find the value of X by taking the antilog of both sides:
1.0/X = 10^(pH - 4.76)
Simplifying this equation will give us the final concentration of CH3COOH, which can be used to calculate the pH:
X = 1.0 / (10^(pH - 4.76))
So, to calculate the pH of the buffer solution, replace "pH" in the equation above with the desired pH value.