Question

36. The dissolution of quartz in H2O can be represented by the following reaction: SiO2 (s) + 2H2O → H4SiO4 (aq) Rimstidt and Barnes (1980) determined the reaction rate for the dissolution of quartz as a function of temperature. Their data are listed in the following table: Temperatures and Reaction Rates for the Dissolution of Quartz T(°C) k(sec-1) 65 105 145 170 213 265 305 3.81 x 10-9 8.15 X 10-9 1.36 x 10-7 7.68 X 10-8 1.05 x 10-6 1.85 x 10-6 3.69 x 10-6 a. Plot log k versus 1/T. Note that temperature should be in Kelvin. b. Using the graph, determine the activation energy for this reaction and the pre- exponential factor.

Can you please answer the question. They are the same question but with clarification/requirements to go with it.

Answer 1

The first step to determine activation energy is to plot a graph if ln(k) and 1/T where T is in kelivn. To convert to kelvin, simply add 273.15 to the temperature in C.

The slope of the resulting line can be used to calculate activation energy, by using the equation

Ea = -slope x R

where R is the gas constant 8.314J/molK

y = -5992.3x - 2.0621 R=0.9523 In(k) 0 0.0005 0.001 0.002 0.0025 0.003 0.0035 0.0015 1/1

From the above graph, the slope can be determined as -5992.3

Thus, the activation energy becomes

Ea = -(-5992.3)x8.314 = 49,819 J/mol or 49.8 KJ/mol