"Calculate the pH of a 1 L solution containing 10 mL of 100 mM glycine and 20 mL of 5 M HCl."
To calculate the pH of a solution, we need to consider the concentration of both the acidic and basic components in the solution and their dissociation constants. In this case, we have glycine (a weak base) and HCl (a strong acid).
To begin, let's calculate the concentration of glycine and HCl in the final solution:
1. glycine:
The initial concentration of glycine is given as 100 mM (millimolar).
We have 10 mL of glycine, so we need to convert it to liters:
10 mL = 10/1000 = 0.01 L
Now, we can calculate the concentration of glycine in the final solution:
Concentration (C) = (moles of solute) / (volume of solution)
C = 100 mM = 0.1 M
Therefore, the concentration of glycine is 0.1 M.
2. HCl:
We have 20 mL of 5 M HCl.
To convert mL of HCl to Liters:
20 mL = 20/1000 = 0.02 L
The concentration of HCl in the final solution is 5 M.
Since HCl is a strong acid and completely ionizes in water, it will release H+ ions into the solution. The concentration of H+ ions in the final solution will be 5 M.
Now, let's proceed to calculate the pH of the solution using a balanced chemical equation:
HCl + glycine ⇌ H+ + Cl- + glycine
Given that the concentration of H+ ions is 5 M, we can directly calculate the pH using the formula:
pH = -log[H+]
Substituting the concentration of H+ ions in the equation:
pH = -log(5)
Using a scientific calculator:
pH ≈ -0.7
Therefore, the pH of the solution is approximately -0.7.