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Experimental measurements of rxn rates
VolumeChanges of a Gas
eudiometer
Volume (mL) 4.0 5.1 5.9 6.8 7.6 8.3
Time (s) 0 15 30 45 60 75
Zn(s) + 2HCl(aq) → H2(g) + ZnCl2(aq)
Rate in mL/s H2
Rate in mol/min for H2
Rate in g/h for HCl
15 30 45 60 75 (time sec)
Volume (mL)
87654321
0
Rise:8.3-4 = 4.3
Run: 75-0 = 75
Slope=Rise/Run=4.3/75=0.057 mL/s
Changes in Pressure
(constant volume or sealed container)
• if more moles of gas (coefficient) in products, pressure will go up
Zn(s) + 2HCl(aq) H2(g) + ZnCl2(aq)
____m.o.g. ____ m.o.g.
• If more MOG in reactants, pressure will __________________________
• rate = ∆ pressure (constant volume)
∆ time
If equal MOG, pressure will not change: NO2(g) + CO(g) CO2(g) + NO(g) 2 m.o.g. 2 m.o.g.
Mass of an open container {Changes in Mass}
Mass (g) 82.07 81.84 81.71 81.66 81.64 81.63
Time (s) 0 15 30 45 60 75
CaCO3(s) + 2HCl(aq) → CO2(g) + CaCl2(aq) + H2O(l)
CaCO3(s) + 2HCl(aq) → CO2(g) + CaCl2(aq) + H2O(l)
1. Calculate the rate in units of grams/s for CO2
2. Calculate the rate in grams/h for CaCO3
Hebden p 5 exercises: 7-9 + Page 11 questions
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