Question

The Kb of ammonia is 1.77 × 10-5. The pH of a buffer prepared by combining 50.0 mL of 1.00 M ammonia and 50.0 mL of 1.00 M ammonium nitrate is __________.

Answer 1

The Kb of ammonia is 1.77 * 10^-5. The pH of a buffer prepared by combining 50.0 mL of 1.00 M ammonia and 50.0 mL of 1.00 M ammonium nitrate is 9.25

Step-by-step explanation:

Step 1: Data given

Kb of ammonia is 1.77 * 10^-5

Volume of ammonia is 50.0 mL = 50*10^-3L

Molarity of ammobia is 1.00 M

Volume of ammonium nitrate is 50.0 mL = 50*10^-3L

Molarity of ammonium nitrate is 1.00 M

Step 2: Calculate moles of ammoniumnitrate

Number of moles = molarity * volume

Number of moles NH4NO3 = 1 M * 0.05 L = 0.05 mol

Step 3: Calculate moles of ammonia

Number of moles = molarity * volume

Number of moles NH3 = 1 M * 0.05 L = 0.05 mol

Step 4: Calculate pH

pOH = - logKb + log [NH4NO3] /[NH3 ]

pOH= - log 1.77x10^-5 + log 1

= 4.752

Since pOh + pH = 14

pH = 14 - pOH = 14 - 4.752 = 9.248

pH ≈ 9.25

The Kb of ammonia is 1.77 * 10^-5. The pH of a buffer prepared by combining 50.0 mL of 1.00 M ammonia and 50.0 mL of 1.00 M ammonium nitrate is 9.25