A buffer solution is prepared by mixing 80.0 mL of 0.20 M NaH2PO4 and 120.0 mL of 0.20 M Na2HPO4.What is the pH of the resulting solution?

Plug into the HH equation and solve. About as simple as you can get. Follow up if you still have a problem.

Well, ready for a little chemistry circus act? Here we go!

To find the pH of the resulting solution, we can use the Henderson-Hasselbalch equation. This equation relies on the ratio of the concentration of the conjugate acid (NaH2PO4) to the concentration of the conjugate base (Na2HPO4).

The pKa of NaH2PO4 is 7.2, which means that at this pH, equal amounts of the acid and base forms are present.

Using the Henderson-Hasselbalch equation: pH = pKa + log([conjugate base]/[conjugate acid])

We can plug in the given values:

pH = 7.2 + log(120.0 mL / 80.0 mL)

Now let's do some math... (sound of a clown juggling numbers)

pH = 7.2 + log(1.5)

And the juggling continues...

pH ≈ 7.2 + 0.18

Finally, the grand finale...

pH ≈ 7.38

Ta-da! The pH of the resulting solution is approximately 7.38. Hope that pHunny enough for you!

To find the pH of the resulting solution, we need to consider the equilibrium between the acid (NaH2PO4) and its conjugate base (Na2HPO4). This buffer system is called a phosphate buffer, which consists of a weak acid (H2PO4-) and its conjugate base (HPO4^2-). The key to buffering is maintaining a relatively constant pH when small amounts of acid or base are added.

To calculate the pH of a buffer solution, we can use the Henderson-Hasselbalch equation:

pH = pKa + log([conjugate base]/[acid])

First, we need to determine the pKa value for the phosphate buffer system. The pKa value can be found in reference books or online sources. For the phosphate buffer, the pKa value is approximately 7.21.

Next, we need to determine the concentrations of the conjugate base ([HPO4^2-]) and acid ([H2PO4-]) in the buffer solution.

Step-by-step calculation:

1. Convert the volumes of the solutions into liters:
Volume of NaH2PO4 solution = 80.0 mL = 0.08 L
Volume of Na2HPO4 solution = 120.0 mL = 0.12 L

2. Calculate the moles of acid and conjugate base:
Moles of NaH2PO4 = concentration (M) x volume (L)
Moles of NaH2PO4 = 0.20 M x 0.08 L = 0.016 mol
Moles of Na2HPO4 = concentration (M) x volume (L)
Moles of Na2HPO4 = 0.20 M x 0.12 L = 0.024 mol

3. Calculate the concentrations of the acid and conjugate base:
Concentration of NaH2PO4 = moles/volume (L)
Concentration of NaH2PO4 = 0.016 mol/0.08 L = 0.20 M
Concentration of Na2HPO4 = moles/volume (L)
Concentration of Na2HPO4 = 0.024 mol/0.12 L = 0.20 M

4. Substitute the values into the Henderson-Hasselbalch equation:
pH = 7.21 + log(0.20/0.20)

Since the concentration of the conjugate base ([HPO4^2-]) is the same as the concentration of the acid ([H2PO4-]), the logarithm part of the equation becomes log(1), which is equal to 0.

5. Simplify the equation:
pH = 7.21 + 0
pH = 7.21

Therefore, the pH of the resulting solution is 7.21.

Note: Buffer solutions resist changes in pH when small amounts of acid or base are added, making them useful in maintaining stable conditions in various chemical and biological processes.