# Do acids and bases have the same coefficients if they neutralize one another?

The questions states: Ammonia has the formula $$\ce{NH3}$$. Household ammonia is a dilute aqueous solution of $$\ce{NH3}$$. Aqueous ammonia is a base that can neutralize acids.

If 18.2 mL of 0.800 M $$\ce{HCl}$$ solution are needed to neutralize 5.00 mL of a household ammonia solution, what is the molar concentration of the ammonia? Express your answer with the appropriate units.

I used the values I was given; converted the $$\ce{HCl}$$ to moles; divided the moles of $$\ce{HCl}$$ by the liters of ammonia solution. However, I do not understand why this is correct.

$$\ce{HCl}$$ is an acid and $$\ce{NH3}$$ is a base. How does finding the molar mass of $$\ce{HCl}$$ help one calculate the molarity of $$\ce{NH3}$$?

Look at the chemical equation. One mole of $\ce{HCl}$ will neutralize one mole of $\ce{NH3}$. $\ce{HCl}$ is an acid so it loses a hydrogen ion and ammonia is a base so it gains a hydrogen ion.
$\ce{HCl + NH3 -> NH4Cl}$
So, you found the number of moles $\ce{HCl}$ added, and this equals the number of moles in the 5.00 mL sample of $\ce{NH3}$. Divide that by the volume and you get concentration, which is moles per liter. You don't need to find the molar mass of $\ce{HCl}$ and you didn't find it as described in your calculations above.