TO HAC SOLUTION (02M 100ml) we add NaOH (0.12M 80ml)
what is the ph
(answer: 4.71)
Where's the decimal in 02M?
To determine the pH of the solution, we need to calculate the concentration of the H+ ions in the resulting solution after the reaction between the acid and base.
Step 1: Begin by writing the balanced chemical equation for the reaction between HAc (acetic acid) and NaOH (sodium hydroxide):
HAc + NaOH → NaAc + H₂O
Step 2: Determine the moles of acetic acid and sodium hydroxide used in the reaction:
Moles of HAc = molarity of HAc × volume of HAc solution
= 0.02 M × 0.1 L
= 0.002 moles
Moles of NaOH = molarity of NaOH × volume of NaOH solution
= 0.12 M × 0.08 L
= 0.0096 moles
Step 3: Based on the stoichiometry of the reaction, determine which reactant is in excess. In this case, NaOH is in excess because there are more moles of NaOH than HAc.
Step 4: Calculate the moles of HAc that reacted:
Moles of HAc reacted = Moles of NaOH × (1 mole HAc / 1 mole NaOH)
= 0.0096 moles × (1 mole HAc / 1 mole NaOH)
= 0.0096 moles
Step 5: Calculate the remaining moles of HAc in the solution:
Moles of HAc remaining = Moles of HAc initially - Moles of HAc reacted
= 0.002 moles - 0.0096 moles
= -0.0076 moles
Note: The negative value indicates that all the acetic acid has reacted with excess sodium hydroxide, resulting in an excess of sodium acetate (NaAc) in the solution.
Step 6: Calculate the concentration of the remaining HAc in moles per liter (M):
Concentration of HAc = Moles of HAc remaining / Volume of the solution in liters
= -0.0076 moles / 0.1 L
= -0.076 M
Note: The negative value indicates that the concentration of remaining HAc is below zero, which is not physically possible. Therefore, we assume that all the acetic acid has reacted and converted to sodium acetate (NaAc).
Step 7: Calculate the pOH of the resulting solution:
pOH = -log[OH-]
= -log(0.12 M)
≈ 0.92
Step 8: Calculate the pH of the solution:
pH + pOH = 14
pH = 14 - pOH
= 14 - 0.92
≈ 13.08
Therefore, the pH of the resulting solution is approximately 13.08.