Calculate the pH of a buffer solution made by adding 0.1 moles of solid Methylammonium nitrate to 120mL of 0.225Molar Of methyl amine
To calculate the pH of a buffer solution, you need to know the concentrations of the acid and its conjugate base. In this case, methylamine (CH3NH2) is the base, and the conjugate acid is methylammonium (CH3NH3+).
Step 1: Calculate the moles of methylamine (CH3NH2):
Moles = volume (in liters) × concentration
= 120 mL × (1 L/1000 mL) × 0.225 M
= 0.027 moles
Step 2: Calculate the moles of methylammonium (CH3NH3+):
Since 0.1 moles of methylammonium nitrate (CH3NH3NO3) are added to the solution, the moles of methylammonium are also 0.1.
Step 3: Calculate the total moles of the base (methylamine) and its conjugate acid (methylammonium):
Total moles = moles of base + moles of conjugate acid
= 0.027 moles + 0.1 moles
= 0.127 moles
Step 4: Calculate the concentration of the base and its conjugate acid in the buffer solution:
Concentration = moles / volume (in liters)
= 0.127 moles / (120 mL × (1 L/1000 mL))
≈ 1.06 M
The concentration of the base (methylamine) and its conjugate acid (methylammonium) in the buffer solution is approximately 1.06 M.
Step 5: Calculate the pKa of the conjugate acid (methylammonium):
The pKa value represents the acidity of the conjugate acid and can be found in reference tables or using experimental data. Let's assume the pKa of methylammonium is 10.0.
Step 6: Calculate the pH of the buffer solution:
pH = pKa + log(concentration of conjugate acid / concentration of the base)
= 10.0 + log(1.06 / 1.06)
= 10.0 + 0
= 10.0
Therefore, the pH of the buffer solution is 10.0.