if equal volumes of solutions having pH6 and pH7 are mixed what is the resulting pH?
It isn't pH 6.5.
You must determine (H^+) from pH 6 and (H^+) from pH 7, average them, then determine pH from that new (H^+).
great thanks a lot, soz bout double post
Here are the initial steps of the solution DrBob suggested:
Let V = liters of solution.
moles of H+ with pH 6 is = 1.00x10^-6)(V)
The total moles of H+ in the mixture is:
moles H+ = (1.00x10^-6)(V)+(1.00x10^-7)(V)
[H+] = (moles H+)/V
To determine the resulting pH when equal volumes of solutions with pH 6 and pH 7 are mixed, we need to understand pH and how it is calculated.
The pH scale is a measure of the acidity or basicity (alkalinity) of a solution. It is defined mathematically as the negative logarithm (base 10) of the concentration of hydrogen ions ([H+]) in a solution. The pH scale ranges from 0 to 14, where pH below 7 indicates acidity, pH above 7 indicates basicity (alkalinity), and pH 7 represents neutral conditions.
When two solutions of different pH are mixed, the resulting pH can be calculated using a formula known as the weighted average.
Here is the step-by-step process to calculate the resulting pH:
1. Convert the pH values to their corresponding hydrogen ion concentration ([H+]) using the formula: [H+] = 10^(-pH).
For pH 6: [H+] = 10^(-6) = 0.000001 M
For pH 7: [H+] = 10^(-7) = 0.0000001 M
2. Calculate the total volume of the mixed solution by adding the volumes of the two equal volumes mixed.
For example, if we mix equal volumes of both solutions, let's assume 100 mL each, then the total volume would be 200 mL.
3. Calculate moles of hydrogen ions present in each solution by multiplying the [H+] concentration by the volume of the solution.
For pH 6 solution: Moles of H+ = 0.000001 M x 100 mL = 0.000001 mol
For pH 7 solution: Moles of H+ = 0.0000001 M x 100 mL = 0.0000001 mol
4. Add the moles of hydrogen ions from both solutions.
Total moles of H+ = 0.000001 mol + 0.0000001 mol = 0.0000011 mol
5. Calculate the final concentration of hydrogen ions ([H+]) in the mixed solution by dividing the total moles by the total volume.
[H+] = 0.0000011 mol / 200 mL = 0.0000000055 M
6. Calculate the resulting pH using the formula: pH = -log([H+]).
pH = -log(0.0000000055)
pH ≈ 7.26
Therefore, the resulting pH when equal volumes of solutions with pH 6 and pH 7 are mixed is approximately 7.26.