Chemistry teacher support material
Investigation 3
Determining ∆H of a Redox Reaction:
DCP
1
Data Collection:
Quantitative Observations:
Mass of zinc powder: 4.31 ± 0.01 g
Volume of CuSO4 (aq): 20.00 ± 0.3 ml
Time of
mixing
Time / m:s
0
:30
1:00
1:30
2:00
2:30
3:00
3:30
4:00
4:30
5:00
5:30
6:00
6:30
7:00
7:30
8:00
8:30
9:00
9:30
10:00
10:30
11:00
11:30
12:00
Temperature / ± 0.2°C
25.1
25.1
25.1
25.1
25.1
25.0
28.1
28.5
33.0
39.1
48.0
53.6
57.2
58.9
57.6
55.1
54.0
53.0
51.3
50.3
48.0
47.5
46.3
46.0
45.0
Qualitative Observations:
Before:
CuSO4 (aq):
Blue clear solution
Same consistency as water
Zinc:
Greyish, dull metal
powder; not fine
During:
Gradually solution became
more clear.
Dark flakes started to form
on bottom of cup.
After:
Dark, greyish black
precipitate
Large flakes, dull matter
colour
Suspended in a clear
colourless solution
© International Baccalaureate Organization 2007
Chemistry teacher support material
Investigation 3
2/3
DATA PRESENTATION:
Time vs Temp. of CUSO4 (aq) + Zn (s) Reaction
80.0
70.0
60.0
Temperature / C
DCP
50.0
40.0
30.0
20.0
0.0
2.0
4.0
6.0
8.0
10.0
12.0
Time / min
© International Baccalaureate Organization 2007
Chemistry teacher support material
Investigation 3
Data Procesing:
DCP
2/3
Balanced Chemical Equation: Zn (s) + CuSO4 (aq) → Cu (s) + ZnSO4 (aq)
Net Ionic Equation: Zn (s) + Cu2+ (aq) → Zn2+ (aq) + Cu (s)
i)
Calculate ∆T:
From graph: Final T extrapolated to be 76.0 ± 0.2°C
Initial T extrapolated to be 25.1 ± 0.2°C
∆T = Tfinal − Tinitial
= (76.0 ± 0.2°C) − (25.1 ± 0.2°C)
= 50.9 ± 0.4°C;% uncerta int y =
= 50.9 ± 0.79%°c
ii)
0.4
x100 = 0.79%
50.9
Calculate Q:
Assuming: Density of solution = 1.00 g/ml; thus 20.0 ml solution will have a
mass = 20.0g
Specific heat of solution = 4.184J/g°C
Q = mc∆T
= (20.0 g...