A solution is prepared by adding 500 mL of 0.300 mol/L of carbonic acid solution and 500 mL of 0.150 mol/L sodium hydrogen carbonate solution. The Ka value for carbonic acid is 4.4 x 10-7. What is the pH of the resultant buffer solution?

To solve this problem, we will use the Henderson-Hasselbalch equation, which is pH = pKa + log([A-]/[HA]), where [A-] is the concentration of the base (sodium hydrogen carbonate) and [HA] is the concentration of the acid (carbonic acid).

Step 1: Calculate the moles of acid and base Moles of acid (HA) = volume (L) x concentration (mol/L) = 0.500 L x 0.300 mol/L = 0.150 mol Moles of base (A-) = volume (L) x concentration (mol/L) = 0.500 L x 0.150 mol/L = 0.075 mol

Step 2: Calculate the total volume of the solution Total volume = volume of acid + volume of base = 0.500 L + 0.500 L = 1.000 L

Step 3: Calculate the concentrations of the acid and base in the new volume Concentration of acid = moles/volume = 0.150 mol / 1.000 L = 0.150 mol/L Concentration of base = moles/volume = 0.075 mol / 1.000 L = 0.075 mol/L

Step 4: Calculate the pKa from the Ka pKa = -log(Ka) = -log(4.4 x 10^-7) = 6.36

Step 5: Substitute the values into the Henderson-Hasselbalch equation pH = pKa + log([A-]/[HA]) = 6.36 + log(0.075/0.150) = 6.36 - 0.30 = 6.06

So, the pH of the resultant buffer solution is approximately 6.06.