Calculate the pH of a solution made by combining 40.0 ml of a 0.14 molar HBrO and 5.0 ml of 0.56 molar NaOH
40.0 mL x 0.14 M HBrO = 5.60 millimols
5.0 mL x 0.56 M NaOH = 2.8 mmols.
.........HBrO + NaOH ==> NaBrO + H2O
I........5.60
add.............2.80..............
C.......-2.80..-2.80.....+2.80
E........2.80....0........2.80
Use the Henderson-Hasselbalch equation with the E line above to solve for pH
To calculate the pH of the solution, we need to determine the concentration of H+ ions in the solution. Here's how to do that:
Step 1: Write the balanced chemical equation for the reaction between HBrO and NaOH.
HBrO + NaOH → NaBrO + H2O
This equation shows that one mole of HBrO reacts with one mole of NaOH to form one mole of NaBrO and one mole of H2O.
Step 2: Determine which reactant is limiting.
To determine which reactant is limiting, compare the number of moles of each reactant. We can use the equation C = n/V, where C is the concentration, n is the number of moles, and V is the volume.
For HBrO:
C(HBrO) = 0.14 M
V(HBrO) = 40.0 ml = 0.040 L
n(HBrO) = C(HBrO) * V(HBrO) = 0.14 M * 0.040 L = 0.0056 moles
For NaOH:
C(NaOH) = 0.56 M
V(NaOH) = 5.0 ml = 0.0050 L
n(NaOH) = C(NaOH) * V(NaOH) = 0.56 M * 0.0050 L = 0.0028 moles
Comparing the number of moles, we can see that NaOH is the limiting reactant because it has fewer moles than HBrO.
Step 3: Calculate the number of moles of H+ ions produced.
From the balanced equation, we can see that one mole of HBrO produces one mole of H+ ions. Therefore, the number of moles of H+ ions is equal to the number of moles of NaOH, which is 0.0028 moles.
Step 4: Calculate the concentration of H+ ions.
To find the concentration of H+ ions, we divide the number of moles of H+ ions by the total volume of the solution.
Total volume = 40.0 ml + 5.0 ml = 45.0 ml = 0.045 L
Concentration(H+) = n(H+) / Total Volume
Concentration(H+) = 0.0028 moles / 0.045 L = 0.0622 M
Step 5: Calculate the pH.
To calculate the pH, we use the formula:
pH = -log[H+]
pH = -log(0.0622)
pH = 1.21
Therefore, the pH of the solution is approximately 1.21.