Chemistry Lab

Investigating Chemical Equilibrium
(Experiment 19 A)

Purpose:
1. to recognize the macroscopic properties of five chemical systems at equilibrium
2. to observe shifts in equilibrium concentrations as stresses are applied to the systems
3. to observe a shift in equilibrium concentrations associated with changes in temperature
4. to explain the observations obtained by applying Le Chatelier’s principle
Materials Required: See page 209 Heath Chemistry Laboratory Experiments

Procedure:
See pages 209-211 Heath Chemistry Laboratory Experiments

Data and Observations:

Table 1 Equilibrium Involving Thymol Blue
REAGENT ADDED STRESS
(ION ADDED) COLOR
OBSERVATION DIRECTION OF
EQUILIBRIUM SHIFT
HCl (Step 3)
HCl (Step 4)
NaOH (Step 5)
NaOH (Step 6)

Table 2 Equilibrium Involving Thiocyanatoiron (III) Ion
REAGENT ADDED STRESS
(ION ADDED) OBERSERVATION DIRECRTION OF
EQUILIBRIUM SHIFT
KCl (test tube B)
Fe(NO3)3 (test tube C)
KSCN (test tube D)
NaOH (test tube E)

Table 3 Equilibrium Involving Cobalt (II) Complexes STRESS OBSERVATION DIRECTION OF EQUILIBRIUM SHIFT
Step 3
Step 4
Step 5

Table 4 Equilibrium Involving Chromate and Dichromate Ions
Steps
2 and 3 0.1 M K2CrO4 0.1 M K2Cr2O7 Initial Color 1 M NaOH added 1 M HCl added
Step 4 0.1 M K2CrO4 0.1 M K2Cr2O7 Initial Color 1 M HCl added 1 M NaOH added
Steps
5 and
6 INITIAL COLOR + 1 M NaOH + 0.1 M Ba(NO3)2 + 1 M HCl 0.1 M K2CrO4 Steps
7 and 8 INITIAL COLOR + 1 M HCl + 0.1 M Ba(NO3)2 + 1 M NaOH 0.1 M K2Cr2O7 Step 9 0.1 M K2CrO4 0.1 M K2Cr2O7 Add 0.1 M Ba(NO3)2

Table 5 Equilibrium Involving Copper (II) Complexes 0.1 M CuSO4 + 3 DROPS NH3 + MORE NH3 1 M HCl ADDED