100ml solution made up 1.0M NH3 and (NH4)2SO4 have been added with 100ml of 0.1 HCl. how many moles are present in the solution before and after? given the pH of the solution is 9.26

To determine the number of moles present in the solution before and after the reaction, we need to use the concept of stoichiometry.

Before the reaction:
- We have 100 mL of a 1.0 M NH3 solution, which means that we have 1.0 mole of NH3 dissolved in this solution.
- We also have 100 mL of a 0.1 M HCl solution, which means that we have 0.1 moles of HCl dissolved in this solution.

After the reaction, NH3 reacts with HCl in a 1:1 molar ratio to form NH4Cl:
NH3 + HCl -> NH4Cl

Since the reaction is stoichiometric, the moles of HCl reacted will be equal to the moles of NH3 reacted.

Therefore, after the reaction:
- The number of moles of NH3 that have reacted is equal to the number of moles of HCl, which is 0.1 moles.
- The remaining moles of NH3 is 1.0 mole (initial amount) - 0.1 moles (reacted) = 0.9 moles.
- The moles of NH4Cl formed is also 0.1 moles.

To calculate the molar concentration of NH3 before the reaction:
- Use the formula: Concentration (M) = moles / volume (L)
- Convert the volume of the solution from 100 mL to 0.1 L (since 1 L = 1000 mL)
- Concentration of NH3 before the reaction = 1.0 mole / 0.1 L = 10 M

To determine the number of moles in the solution after the reaction, we need to add the moles of NH3 (0.9 moles) and NH4Cl (0.1 moles):
- Total moles in the solution after the reaction = 0.9 moles + 0.1 moles = 1.0 moles

Given that the pH of the solution is 9.26, it suggests that NH3 (ammonia) is acting as a base and has partially dissociated, resulting in the presence of NH3 and NH4+ ions. The concentration of NH3 and NH4+ can be used to calculate the pH. However, further information or equations are needed to determine the concentrations of NH3 and NH4+ ions in the solution.