Determine the concentration of 20.0 mL of the sulphuric acid when 1.00 mol/L sodium hydroxide is used as the titrant.
Observations: Initial volume of H2SO4 __________.
Final volume of H2SO4 __________.
Volume of H2SO4 added __________.
To determine the concentration of the sulfuric acid (H2SO4) using sodium hydroxide (NaOH) as the titrant, we need to perform a titration. In this titration, sodium hydroxide will react with sulfuric acid in a 1:1 ratio according to the balanced chemical equation:
H2SO4 + 2NaOH -> Na2SO4 + 2H2O
In this case, we have 20.0 mL of sulfuric acid and 1.00 mol/L sodium hydroxide. The steps to determine the concentration of sulfuric acid are as follows:
1. Prepare the burette: Fill a burette with the sodium hydroxide solution, taking note of the initial volume (let's call this Vi). Make sure to record the volume in milliliters (mL).
2. Transfer the sulfuric acid: Measure 20.0 mL of sulfuric acid using a pipette or a volumetric flask into a clean and dry flask. Add a few drops of an appropriate indicator (e.g., phenolphthalein) to the flask.
3. Perform the titration: Slowly add the sodium hydroxide solution from the burette into the flask containing the sulfuric acid while swirling the flask. Stop adding sodium hydroxide when the indicator shows a persistent color change.
4. Record the final volume of sodium hydroxide (Vf) in the burette.
5. Calculate the volume of sodium hydroxide used in the titration (Vt): Vt = Vf - Vi. Make sure to use the same units.
6. Calculate the moles of sodium hydroxide used in the titration: Moles(NaOH) = concentration(NaOH) * volume(NaOH)
7. Since the stoichiometry of the reaction is 1:1 (1 mole of H2SO4 reacts with 1 mole of NaOH), the moles of sulfuric acid present in the 20.0 mL solution is also equal to Moles(NaOH).
8. Finally, calculate the concentration of sulfuric acid: Concentration(H2SO4) = Moles(H2SO4) / Volume(H2SO4)
By following these steps and recording the initial and final volumes of the sulfuric acid, you should be able to determine its concentration.