Calculate the pH of the the solution that results from titrating 50 mL of 0.6 M NaOCl(aq) with 0.3 M HBr
At 0.00 mL of HBr:
At 70 mL of HBr:
At 100 mL HBr:
At 120 mL of HBr
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To calculate the pH of the solution resulting from the titration, we need to determine the amount of HBr that has reacted with NaOCl at each point and calculate the concentration of H+ ions in the solution.
1. At 0.00 mL of HBr:
At this point, no HBr has been added to the solution. The pH can be determined using the dissociation of NaOCl:
NaOCl(aq) + H2O(l) ↔ Na+(aq) + OCl-(aq) + H2O(l)
Since NaOCl is a strong base and H2O is a neutral species, we have Na+(aq) and OCl-(aq) as the main species. The OCl- ion is the conjugate base of a weak acid, HOCl, which can hydrolyze to produce H+ ions:
OCl-(aq) + H2O(l) ↔ HOCl(aq) + OH-(aq)
Since NaOCl is a strong base, we can assume that it completely dissociates, and thus the OH- concentration is equal to the initial NaOCl concentration (0.6 M) divided by the volume (50 mL):
[OH-] = (0.6 M)/(0.05 L) = 12 M
To determine the concentration of H+ ions, we can use the equilibrium expression for water:
Kw = [H+][OH-]
Since Kw is a constant at a given temperature (1.0 x 10^-14 at 25°C), we can rearrange the equation to solve for [H+]:
[H+] = Kw / [OH-]
Plugging in the values, we get:
[H+] = (1.0 x 10^-14) / (12 M) = 8.3 x 10^-14 M
To calculate the pH, we take the negative logarithm of the [H+] concentration:
pH = -log[H+] = -log(8.3 x 10^-14) ≈ 13.08
Therefore, at 0.00 mL of HBr, the pH of the solution is approximately 13.08.
2. At 70 mL of HBr:
To calculate the pH at this point, we need to determine the number of moles of HBr that have reacted with NaOCl. Since we are adding 0.3 M HBr, the moles of HBr added can be found using the formula:
moles = concentration x volume
moles of HBr = (0.3 M) x (0.07 L) = 0.021 moles
Assuming a 1:1 stoichiometry between HBr and NaOCl, this means that 0.021 moles of NaOCl have reacted. Then, we can subtract this value from the initial moles of NaOCl (0.6 M x 0.05 L) to find the remaining moles:
moles of NaOCl remaining = (0.6 M x 0.05 L) - 0.021 moles = 0.009 moles
Now we can calculate the new concentration of NaOCl:
[NaOCl] = moles / volume = 0.009 moles / 0.05 L = 0.18 M
Using the same process as before, we can determine the concentration of OH- ions and then use that to find the concentration of H+ ions. Finally, we can calculate the pH.
3. At 100 mL of HBr:
Follow the same steps as in point 2, but this time, use 0.1 L as the volume in the calculations.
4. At 120 mL of HBr:
Follow the same steps as in point 2, but this time, use 0.12 L as the volume in the calculations.
Remember to recalculate the concentrations of NaOCl, OH-, and H+ ions at each point before determining the pH of the solution.