Titration Calculations in Chemistry

Titration and Concentration Calculations

Overview of Titration

  • Titration is a laboratory method used to determine the concentration of a dissolved substance (analyte) by reacting it with a solution of known concentration (titrant).
  • In this case, the titrant is soda (NaOH) and the analyte is hydrochloric acid (HCl).

Given Data

  • Volume of NaOH solution (titrant): 12.5 mL
  • Molarity of NaOH solution (titrant): 0.143 M
  • Volume of HCl solution (analyte): 25.0 mL

Calculation Steps

  • To calculate the concentration of the HCl solution, the following steps are followed:
1. Determine Moles of NaOH Used
  • The number of moles of NaOH can be calculated using the formula:
    Moles=Molarity×Volume (L)\text{Moles} = \text{Molarity} \times \text{Volume (L)}
  • Convert volume from mL to L:
    12.5 mL=0.0125 L12.5 \, \text{mL} = 0.0125 \, \text{L}
  • Calculate moles:
    Moles of NaOH=0.143 mol/L×0.0125 L=0.0017875 mol\text{Moles of NaOH} = 0.143 \, \text{mol/L} \times 0.0125 \, \text{L} = 0.0017875 \, \text{mol}
2. Stoichiometry of the Reaction
  • The balanced chemical equation for the neutralization reaction is:
    NaOH+HCl→NaCl+H2O\text{NaOH} + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O}
  • This equation shows that 1 mole of NaOH reacts with 1 mole of HCl.
3. Determine Moles of HCl
  • Since the ratio of NaOH to HCl is 1:1, the moles of HCl can be determined directly:
    Moles of HCl=Moles of NaOH=0.0017875 mol\text{Moles of HCl} = \text{Moles of NaOH} = 0.0017875 \, \text{mol}
4. Calculate the Concentration of HCl
  • We can now use the number of moles of HCl and its volume to calculate the molarity using the formula:
    Molarity=MolesVolume (L)\text{Molarity} = \frac{\text{Moles}}{\text{Volume (L)}}
  • Convert the volume of HCl from mL to L:
    25.0 mL=0.0250 L25.0 \, \text{mL} = 0.0250 \, \text{L}
  • Calculate molarity:
    [HCl]=0.0017875 mol0.0250 L=0.0715 M[\text{HCl}] = \frac{0.0017875 \, \text{mol}}{0.0250 \, \text{L}} = 0.0715 \, \text{M}

Final Result

  • The concentration of the HCl solution is:
    [HCl]=0.0715 M (molarity)[\text{HCl}] = 0.0715 \, \text{M} \text{ (molarity)}

Summary

  • Based on the titration data, the concentration of the hydrochloric acid solution (HCl) is determined to be 0.0715 M.