Final answer:
The amount of HCl in moles used in a titration is found by multiplying the volume of HCl solution by its molarity. In an example using 25.66 mL of 0.1078 M HCl, this is 0.002766 mol HCl. Same moles of NaOH react due to the 1:1 mole ratio in the balanced equation.
Step-by-step explanation:
The amount of HCl in moles used in a titration can be calculated by multiplying the volume of the HCl solution (in liters) used in the titration by its molarity (concentration in moles per liter). For example, if 25.66 mL (or 0.02566 L) of 0.1078 M HCl is used, the number of moles of HCl reacted with the unknown sample of NaOH would be calculated as follows:
# mol HCl = 0.02566 L × 0.1078 M = 0.002766 mol HCl
With the balanced chemical equation HCl + NaOH → NaCl + H₂O, we can see that the reaction is a 1:1 mole ratio, indicating that the moles of NaOH are equal to the moles of HCl at the endpoint of the titration. Therefore, the number of moles of NaOH reacted would also be 0.002766 mol. This relationship is essential for calculating the mass of NaOH in the sample.