What is the pH of a solution made by mixing 200 mL of 0.025M HCl and 150 mL of 0.050 M HCl?

The answer to your question is pH = 1.45

Explanation:

Data

pH = ?

Volume 1 = 200 ml

[HCl] 1 = 0.025 M

Volume 2 = 150 ml

[HCl] 2 = 0.050 M

Process

1. - Calculate the number of moles of each solution

Solution 1

Molarity = moles / volume

-Solve for moles

moles = 0.025 x 0.2

result

moles = 0.005

Solution 2

moles = 0.050 x 0.15

-result

moles = 0.0075

2. - Sum up the number of moles

Total moles = 0.005 + 0.0075

= 0.0125

3. - Sum up the volume

total volume = 200 + 150

350 ml or 0.35 l

4. - Calculate the final concentration

Molarity = 0.0125 / 0.35

= 0.0357

5. - Calculate the pH

pH = - log [H⁺]

-Substitution

pH = - log[0.0357]

-Result

pH = 1.45