At pH 9 what will the ratio of ammonium to ammonia be? The pKa of ammonium is 9.24?
To determine the ratio of ammonium (NH4+) to ammonia (NH3) at a specific pH, we need to use the Henderson-Hasselbalch equation:
pH = pKa + log([A-]/[HA])
In this equation, [A-] represents the concentration of the conjugate base (ammonia, NH3) and [HA] represents the concentration of the acid (ammonium, NH4+).
Since we are given the pKa of ammonium as 9.24, we can rearrange the Henderson-Hasselbalch equation to solve for the ratio [A-]/[HA]:
pH - pKa = log([A-]/[HA])
Taking the antilog of both sides of the equation, we get:
10^(pH - pKa) = [A-]/[HA]
Now, let's substitute the given values into the equation:
pH - pKa = 9 - 9.24 = -0.24
Using a calculator, we can calculate the antilog of -0.24:
10^(-0.24) = 0.579
Therefore, the ratio of ammonium to ammonia at pH 9 is approximately 0.579. This means that for every mole of ammonium, there will be approximately 0.579 moles of ammonia.