The pK a of ammonium ions (NH 4 + ) is 9.25. You have one liter of water contain
ID: 788257 • Letter: T
Question
The pKa of ammonium ions (NH4+) is 9.25. You have one liter of water containing 110 mmoles ammonia (NH3), and you add 100 mmoles of HCl. What is the pH of the final solution. This is one you should be able to do without a calculator.The pKa of ammonium ions (NH4+) is 9.25. You have one liter of water containing 110 mmoles ammonia (NH3), and you add 100 mmoles of HCl. What is the pH of the final solution. This is one you should be able to do without a calculator.
The pKa of ammonium ions (NH4+) is 9.25. You have one liter of water containing 110 mmoles ammonia (NH3), and you add 100 mmoles of HCl. What is the pH of the final solution. This is one you should be able to do without a calculator.
Explanation / Answer
molarity of NH3=0.11
molarity of HCl=0.1
now HCl+NH3----> NH4Cl
so moles of NH4Cl formed=0.1
so a buffer is formed
so,
pOH=pKb+log([salt]/[base])
=(14-9.25)+log(0.1/0.01)
=5.75
so pH=14-5.75
=8.25