The first in a series of models which use "real" rate constants and equations to allow students to explore equilibrium. The model builds on the earlier HI stoichiometry model. Students should recognise that the moles of reactant can be used because the volume of the reaction will remain the same and thus including the volume will not alter the results. If desired for consistency, it is easy enough to add volume to the calculations, but the model can get ugly. The constants used here are for the reaction at 700K. Here are some other values: T(K) kf kr K 300 2.24e-19 2.04e-16 912 400 2.46e-11 6.69e-9 371 500 1.66e-6 2.14e-4 129 600 2.75e-3 2.14e-1 77.8 Students can use these values to explore various aspects of equilibrium. Be forewarned, when changing the rate constants, it may be necessary to change the time specs of the model. STELLATM software is needed to view the model in Mac (hqx) format or PC format. [Diagram Level | Equations Level | Graphs ] moles_HI(t) = moles_HI(t - dt) + (I2_to_HI + H2_to_HI - HI_to_H2 - HI_to_I2) * dt INIT moles_HI = initial_mol_HI INFLOWS: I2_to_HI = rate_reverse H2_to_HI = rate_reverse OUTFLOWS: HI_to_H2 = rate_forwd HI_to_I2 = rate_forwd moles_hydrogen(t) = moles_hydrogen(t - dt) + (HI_to_H2 - H2_to_HI) * dt INIT moles_hydrogen = initial_mol_H2 INFLOWS: HI_to_H2 = rate_forwd OUTFLOWS: H2_to_HI = rate_reverse moles_iodine(t) = moles_iodine(t - dt) + (HI_to_I2 - I2_to_HI) * dt INIT moles_iodine = initial_mol_I2 INFLOWS: HI_to_I2 = rate_forwd OUTFLOWS: I2_to_HI = rate_reverse initial_mol_H2 = 0.1 initial_mol_HI = 0.1 initial_mol_I2 = 0.1 Keq = moles_hydrogen*moles_iodine/moles_HI^2 k_forward = 0.550 k_rev = 30.2 rate_forwd = k_forward*moles_HI^2 rate_reverse = k_rev*moles_iodine*moles_hydrogen total_moles = moles_HI+moles_hydrogen+moles_iodine Time Specs Range: 0-100 , dT = 0.1 , Integration Method = RK4

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