Concentration Calculation for Sodium Hydroxide

Understanding Concentration Calculations

Key Concepts

  • Concentration Equation:
    • The fundamental equation for concentration is given by:
      Concentration=MolesVolume\text{Concentration} = \frac{\text{Moles}}{\text{Volume}}
    • This equation helps in determining the concentration of a solute in a solution.

Steps for Calculation

  1. Set Up:

    • Use a table for clarity to account for given data and what needs to be calculated.
    • Input known values from the problem statement.

  2. Convert Volume:

    • Convert the volume into decimeters cubed. This is done by dividing the given volume (in mL) by 1000:
      Volume in dm3=Volume in mL1000\text{Volume in dm}^3 = \frac{\text{Volume in mL}}{1000}
    • This is crucial as concentration is typically expressed in moles per decimeter cubed.

  3. Calculate Moles of C₆H₈O₇ (citric acid):

    • Use the concentration of citric acid and calculated volume to find moles:
      Moles of C<em>6H</em>8O7=Concentration×Volume\text{Moles of C}<em>{6}H</em>{8}O_{7} = \text{Concentration} \times \text{Volume}
    • In this case, the calculation yields:
      6.65×10−4 moles6.65 \times 10^{-4} \, \text{moles}

  4. Stoichiometry for Sodium Hydroxide:

    • Establish the molar ratio from the balanced equation. For citric acid (C₆H₈O₇) reacting with sodium hydroxide (NaOH), assume a 1:1 ratio (as stated).
    • Calculate moles of sodium hydroxide accordingly:
      Moles of NaOH=1.995×10−3 moles\text{Moles of NaOH} = 1.995 \times 10^{-3} \, \text{moles}
    • This is derived by multiplying the moles of citric acid by the stoichiometric coefficient (in this case, 3 for NaOH if the reaction consumes three moles per mole of citric acid).

  5. Final Concentration Calculation:

    • Finally, to find the concentration of sodium hydroxide, apply the concentration equation again:
      Concentration of NaOH=Moles of NaOHVolume\text{Concentration of NaOH} = \frac{\text{Moles of NaOH}}{\text{Volume}}
    • Upon calculation:
      Concentration=0.0798 mol/dm3\text{Concentration} = 0.0798 \, \text{mol/dm}^3

Summary

  • This systematic approach confirms how to calculate concentration using given data and stoichiometry.
    • The significance of proper unit conversion and understanding mole ratios is imperative in such calculations.
    • The calculated concentration of sodium hydroxide achieved the three marks as per the examination format.