Table 3.

Aggregated results of the reaction-rate coefficients and activation energies for all grain sizes and temperatures in brine

Grain size (μm)T = 25°C
(mol cm−2 s−1)
T = 100°C
(mol cm−2 s−1)
Ea (kJ mol−1)
Log knLog kn
300 – 350−8.16 ± 0.060.068 ± 0.026−7.61 ± 0.050.08 ± 0.0215.72 ± 2.40
75 – 100−7.88 ± 0.170.26 ± 0.06−7.45*0.17*12.12 ± 4.83
20 – 25−6.62 ± 0.540.54 ± 0.14−5.96 ± 0.980.5 ± 0.318.70 ± 31.82

*The reported value for the 75 – 100 μm grains at 100°C (Experiment 5, Fig. 2) is based on only two data points, which do not fully represent the acidic region. That is why the value is likely to be underestimated. The same applies for the 20 – 25 μm grains at 100°C. The resulting error remains large, yielding an inconclusive value for the activation energy at the small grain size.