Final answer:
The pH after adding 10.00 mL of 0.050 M HCl to a 60.00 mL sample of 0.075 M weak base, calculate the moles of reactants and use them to determine the pOH and pH of the solution. The pH of the solution will be approximately 12.758.
Step-by-step explanation:
To determine the pH after adding 10.00 mL of 0.050 M HCl to a 60.00 mL sample of 0.075 M weak base, we need to consider the reaction between the acid and base. The balanced equation for this reaction is:
HCl(aq) + weak base(aq) → salt(aq) + H2O(l)
The weak base reacts with the HCl to form a salt and water. Since the volume of the weak base is larger than the
volume of HCl, the weak base will be in excess. Therefore, we can calculate the amount of moles of the weak base remaining after the reaction and use it to determine the pOH and pH of the solution.
Step-by-step calculation:
- Calculate the number of moles of HCl used:
- Moles of HCl = Molarity of HCl x Volume of HCl
- Moles of HCl = 0.050 M x 10.00 mL
- Moles of HCl = 0.0005 mol
Calculate the number of moles of the weak base:
- Moles of weak base = Molarity of weak base x Volume of weak base
- Moles of weak base = 0.075 M x 60.00 mL
- Moles of weak base = 0.0045 mol
Calculate the number of moles of weak base remaining:
- Moles of weak base remaining = Initial moles of weak base - moles of weak base used
- Moles of weak base remaining = 0.0045 mol - 0.0005 mol
- Moles of weak base remaining = 0.0040 mol
Calculate the concentration of the weak base:
- Concentration of weak base = Moles of weak base remaining / Volume of the solution
- Concentration of weak base = 0.0040 mol / 70.00 mL
- Concentration of weak base = 0.0571 M
Calculate the pOH:
- pOH = -log(Concentration of the weak base)
- pOH = -log(0.0571)
- pOH = 1.242
Calculate the pH:
- pH = 14.00 - pOH
- pH = 14.00 - 1.242
- pH = 12.758
The pH of the solution after adding 10.00 mL of 0.050 M HCl will be approximately 12.758.