Lab Report for Chemical Equilibrium - Laboratory Write-up...

Laboratory Write-up for Chemical Equilibrium
Chemistry 112 Lab Section 115
October 29, 2014
A. Research Question
1. What is the Kc for the reaction at room temperature?
2. What is the sign of the ΔH for the reaction?
3. What are the effects of adding/removing reactants to/from the equilibrium mixture?
B. Observations and Results
Table 1. Equilibrium Constant Determination
Test tube [Fe 3+ ]
I
(M) [SCN - ]
I
(M) [Fe 3+ ]
eq
(M) [SCN - ]
eq
(M) [FeSCN 2+ ]
eq
(M) K
c
1 0.001 0.0004 8.70 x 10
-4
2.70 x 10
-4
1.30 x 10
-4
553
2 0.001 0.006 8.60 x 10 -4 4.60 x 10 -4 1.40 x 10 -4 354
3 0.001 0.0008 8.44 x 10 -4 6.44 x 10 -4 1.56 x 10 -4 287
4 0.001 0.001 8.19 x 10 -4 8.19 x 10 -4 1.81 x 10 -4 270
Table 2. Le Chatelier’s Principle Observations.
Effect A
470
(indicate ↑ or ↓) Change in [FeSCN 2+ ] (indicate ↑ or ↓)
Adding heat energy ↓ ↓
Removing heat energy ↑ ↑
Adding Fe(NO
3
)
3
↑ ↑
Adding EDTA ↓ ↓
C. Claim
Make a claim about each of the following:
- The K
c
for the reaction at room temperature
- The sign of the ΔH for the reaction
- The effects of adding/removing reactants to/from the equilibrium mixture
1. The K
c
for the reaction at room temperature is 366.
2. The sign of the ΔH for the reaction is negative.
3. Adding reactants to the equilibrium mixture shifts the equilibrium to the right and
removing reactants shifts the equilibrium to the left.