H2 + I2 = HI

hydrogen + iodine ⟶ hydrogen iodide

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: | 2 c_1 = c_3 I: | 2 c_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_1 = 1 and solve the system of equations for the remaining coefficients: c_1 = 1 c_2 = 1 c_3 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | + ⟶ 2

+ ⟶

hydrogen + iodine ⟶ hydrogen iodide

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

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

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

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