What is the PH of a solution that results from mixing together equal volumes of a 0.150 M Solution of acetic acid and a 0.0750 M solution of sodium hydroxide?
Write the reaction. Since no volume is listed, just choose a convenient one and use it for both.
Calculate moles acid and moles base. Determine how much of the salt, sodium acetate, is produced. Determine how much of the acetic acid is left.
Use the Henderson-Hasselbalch equation and solve for pH. Post your work if you get stuck.
To determine the pH of the solution resulting from mixing a solution of acetic acid (CH3COOH) and a solution of sodium hydroxide (NaOH), we need to consider the following:
1. Acetic acid (CH3COOH) is a weak acid, meaning that only a fraction of it will dissociate into ions when dissolved in water.
2. Sodium hydroxide (NaOH) is a strong base, which will fully dissociate into sodium ions (Na+) and hydroxide ions (OH-) when dissolved in water.
3. When the acid and base react, they will undergo a neutralization reaction: CH3COOH + NaOH → NaCH3COO + H2O.
To find the pH, we need to determine the concentration of the resulting NaCH3COO (sodium acetate) solution. Since equal volumes are mixed, we can assume that the final volume is twice the original volume of either solution. Therefore, the concentration of the sodium acetate solution will be half the original concentration of either the acetic acid or sodium hydroxide solution.
1. Calculate the concentration of the resulting sodium acetate solution:
- For the acetic acid solution: The original concentration is 0.150 M. Since we assume the final volume is twice the original volume, the concentration of sodium acetate is 0.150 M / 2 = 0.075 M.
- For the sodium hydroxide solution: The original concentration is 0.0750 M. Again, with the final volume being twice the original, the concentration of sodium acetate is 0.0750 M / 2 = 0.0375 M.
2. Next, we need to determine the concentration of hydroxide ions (OH-) in the resulting sodium acetate solution. Since sodium acetate is the conjugate base of acetic acid, it will hydrolyze in water to produce hydroxide ions.
- Consider the dissociation of sodium acetate (NaCH3COO): NaCH3COO → Na+ + CH3COO^-
- Since the solution is at equilibrium, the concentration of the hydroxide ions will be equal to the concentration of the acetate ions (CH3COO^-).
3. Finally, we can calculate the pOH (potential of Hydroxide) and pH values using the concentration of hydroxide ions (OH-):
- pOH = -log10[OH-]
- pH = 14 - pOH
Substituting the concentration of hydroxide ions in the formula, we can find the pH of the solution resulting from the mixture of acetic acid and sodium hydroxide.