What is the pH of the solution created by combining 2.00 mL of the 0.10 M base[ammonia] with 8.00 mL of the 0.10 M acid[acid acid]?

I tried this problem so many times, but always got it wrong. It's a weak base and acid titration. but i don't know the method of do this type of proble

It's done with moles.

You have acid acid for the acid so I don't know which acid you are using.
mols base = M x L = 0.1 x 0.002 L = xx
mols acid = M x L = 0.1 x 0.008 L = yy
There will be xx mols salt formd.
There will be xx mols acid - yy mols base = excess acid unreacted. All of the base will be gone.
The pH will be that of the acid/salt system but we need to know the acid to proceed.

I believe he was referring to hydrochloric acid

To determine the pH of the solution created by combining a weak base (ammonia) with a weak acid (acid acid), you need to understand the concept of acid-base titration and the relationship between the concentrations of the reacting species.

Here's the step-by-step approach to solving this problem:

1. Write the balanced chemical equation for the reaction between ammonia and acid acid. The reaction can be represented as follows:
NH3 + HX ⇌ NH4X
where X represents the anion of the acid.

2. Determine the limiting reactant. In this case, the reactant that will react completely is the one present in the smallest quantity. To do this, you need to calculate the number of moles of each reactant.

For the base (ammonia):
moles of ammonia = volume (in liters) × concentration (in moles/liter)
moles of ammonia = 0.002 L × 0.1 mol/L

For the acid (acid acid):
moles of acid = volume (in liters) × concentration (in moles/liter)
moles of acid = 0.008 L × 0.1 mol/L

Compare the mole quantities of ammonia and acid to determine the limiting reactant.

3. Calculate the moles of the product formed. Since the limiting reactant will be completely consumed, the number of moles of the product formed will be equal to the number of moles of the limiting reactant.

4. Calculate the final concentration of the product (NH4X) in the combined solution. To do this, divide the moles of the product by the total volume of the solution.

5. Determine whether the product (NH4X) will dissociate in water or remain as a weak acid and base. If the product is a strong acid or base, you can assume it fully dissociates. If it is a weak acid or base, you need to consider its equilibrium dissociation constant (Ka or Kb) and the resulting ion concentrations.

6. Calculate the concentration of the hydronium ion (H3O+) or hydroxide ion (OH-) based on the product's behavior (fully dissociated or weak acid/base). The concentration of the hydronium ion (H3O+) will determine the pH of the solution.

Keep in mind that this is a general approach to solving acid-base titration problems. The specific values and calculations may vary depending on the given data. Make sure to use the correct chemical formulas, balanced equations, and dissociation constants for the specific substances in question.