CP CHEMISTRY
Titration Demo Lab
Name: ________________________________
___ period
Background:
Acid-base titrations involve the neutralization reaction between the hydrogen ions
and hydroxide ions. These ions combine to form neutral water molecules. When
the number of hydrogen ions and hydroxide ions are equal in the titration flask,
then the equivalence point has been reached. In order to see this point, indicators
are used. They are one color in an acidic solution and another color in a basic
solution. Some occur naturally as pigments in plant leaves. In this lab, red
cabbage leaves will be used to make an indicator for the titrations of vinegar with
sodium hydroxide and ammonia with hydrochloric acid.
Purpose:
Observe the properties of an indicator extracted from red cabbage
leaves and use it to determine the concentrations of vinegar and
ammonia solutions.
Data:
Table 1 – Cabbage Indicator
Tube
A
B
C
D
E
Reagent Added
Observation
CP CHEMISTRY, Titration Demo Lab, page 2
Table 2 – Titration of Vinegar
Volume of vinegar (mL)
Molarity of NaOH (M)
Volume of NaOH (mL)
(initial buret reading)
Volume of NaOH (mL)
(final buret reading)
Volume of NaOH used (mL)
Table 3 – Titration of Ammonia
Volume of ammonia (mL)
Molarity of HCl (M)
Volume of HCl (mL)
(initial buret reading)
Volume of HCl (mL)
(final buret reading)
Volume of HCl used (mL)
CP CHEMISTRY, Titration Demo Lab, page 3
Analysis:
1.
Calculate the molarity of the vinegar solution.
2.
Calculate the molarity of the ammonia solution.
Conclusions:
1.
Would you use and acid or base as a standard when titrating against a
solution of soda? Why?
2.
Describe how you could use the red cabbage extract as a quantitative
method for determining solution pH.