HI = H2 + I2

hydrogen iodide ⟶ hydrogen + iodine

Balance the chemical equation algebraically: ⟶ + Add stoichiometric coefficients, c_i, to the reactants and products: c_1 ⟶ c_2 + c_3 Set the number of atoms in the reactants equal to the number of atoms in the products for H and I: H: | c_1 = 2 c_2 I: | c_1 = 2 c_3 Since the coefficients are relative quantities and underdetermined, choose a coefficient to set arbitrarily. To keep the coefficients small, the arbitrary value is ordinarily one. For instance, set c_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 2 c_2 = 1 c_3 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 ⟶ +

⟶ +

hydrogen iodide ⟶ hydrogen + iodine

| hydrogen iodide | hydrogen | iodine molecular enthalpy | 26.5 kJ/mol | 0 kJ/mol | 0 kJ/mol total enthalpy | 53 kJ/mol | 0 kJ/mol | 0 kJ/mol | H_initial = 53 kJ/mol | H_final = 0 kJ/mol | ΔH_rxn^0 | 0 kJ/mol - 53 kJ/mol = -53 kJ/mol (exothermic) | |

| hydrogen iodide | hydrogen | iodine molecular free energy | 1.7 kJ/mol | 0 kJ/mol | 0 kJ/mol total free energy | 3.4 kJ/mol | 0 kJ/mol | 0 kJ/mol | G_initial = 3.4 kJ/mol | G_final = 0 kJ/mol | ΔG_rxn^0 | 0 kJ/mol - 3.4 kJ/mol = -3.4 kJ/mol (exergonic) | |

| hydrogen iodide | hydrogen | iodine Hill formula | HI | H_2 | I_2 name | hydrogen iodide | hydrogen | iodine IUPAC name | hydrogen iodide | molecular hydrogen | molecular iodine

| hydrogen iodide | hydrogen | iodine molar mass | 127.912 g/mol | 2.016 g/mol | 253.80894 g/mol phase | gas (at STP) | gas (at STP) | solid (at STP) melting point | -50.76 °C | -259.2 °C | 113 °C boiling point | -35.55 °C | -252.8 °C | 184 °C density | 0.005228 g/cm^3 (at 25 °C) | 8.99×10^-5 g/cm^3 (at 0 °C) | 4.94 g/cm^3 solubility in water | very soluble | | dynamic viscosity | 0.001321 Pa s (at -39 °C) | 8.9×10^-6 Pa s (at 25 °C) | 0.00227 Pa s (at 116 °C) odor | | odorless |