A 130.0 mL buffer solution is 0.100 M in NH3 amd 0.135 M in NH3 and 0.135 M in NH4Br. What mass of HCI could this buffer neutralize before the pH fell below 9.00?
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To determine the mass of HCl that could be neutralized by the buffer solution before the pH falls below 9.00, we need to calculate the moles of NH3 and NH4Br in the solution.
Step 1: Calculate the moles of NH3 (ammonia):
Molarity (M) = moles/volume(L)
0.100 M = moles/0.130 L
Moles of NH3 = 0.100 M x 0.130 L = 0.013 moles
Step 2: Calculate the moles of NH4Br (ammonium bromide):
Molarity (M) = moles/volume(L)
0.135 M = moles/0.130 L
Moles of NH4Br = 0.135 M x 0.130 L = 0.018 moles
Step 3: Convert the moles of NH3 to moles of HCl:
The moles of NH3 and HCl react with each other in a 1:1 ratio according to the balanced equation:
NH3 + HCl -> NH4Cl
Since the moles of NH3 and HCl are equal, the moles of HCl that can be neutralized is also 0.013 moles.
Step 4: Convert moles of HCl to mass:
Moles of HCl = mass/molar mass
0.013 moles = mass/ molar mass(HCl)
Rearranging the equation, we get:
mass = moles of HCl x molar mass(HCl)
The molar mass of HCl is approximately 36.46 g/mol.
mass = 0.013 moles x 36.46 g/mol = 0.474 g
Therefore, this buffer solution can neutralize around 0.474 grams of HCl before the pH falls below 9.00.