Pre-Laboratory Questions
Consider the following titration: 0.0250 L of HCl are placed in an Erlenmeyer Flask. 40.05 mL of 0.250M NaOH are added from the buret to reach the end point. What is the concentration of the HCl in the Erlenmeyer Flask?
a. First, figure out how many moles of NaOH were added to the flask. (Start with 40.05 mL. Remember that 0.250 M means 0.250 moles / 1 L.)
Show your calculation. Use units with numbers. Report your answer with three sig.figs.
b. Then figure out how many moles of HCl are in the Erlenmeyer flask. Use the balanced equation from the introduction of this lab.
Show your calculation. Use units with numbers. Report your answer with three sig.figs.
c. Finally, calculate the concentration of HCl in molarity. Use the moles you calculated for HCl and use 0.0250 L since that is the volume of HCl. Remember that M = mol/L or: molarity is equal to moles ÷ L.
Show your calculation. Use units with numbers. Report your answer with three sig.figs.