N2. ANALYSIS OF CONCENTRATED ACID
PURPOSE: To design and carry out a procedure for the determination of the molarity of a
concentrated laboratory acid by titration with standardised 0.1M NaOH
PREWORK: This is a group-work exercise and is to be completed and submitted prior to
commencement of the experiment
You will be assigned one of the concentrated acids below. Write out fully the steps required to
determine the molarity of the acid you are assigned. The molarities are as follows:
Hydrochloric (HCl) 11.3 M
Sulfuric (H2SO4) 18 M
Nitric (HNO3) 16 M
Your procedure must include:
• Dilution steps (note that you should not use volumetric flasks greater than 250 mL or
pipettes less than 5 mL).
• Aliquot volume and indicator to be used in the titration of the diluted acid
• A method for determining the density of the concentrated acid
CALCULATIONS
1. Write a balanced equation for the reaction
2. Calculate the moles of NaOH used in the titration and therefore determine the moles
of acid involved in the titration
3. Calculate the molarity of the diluted acid
4. Calculate the molarity of the concentrated acid
5. Convert the molarity of the concentrated acid to %w/w (g/100g) of the acid
QUESTIONS
1. Compare your answer for molarity to the accepted value. Account for any differences
2. Why is it desirable to have endpoint volumes of a titration between 15 and 30 mL of
titrant?
3. What is serial dilution? What are its advantages and disadvantages?