Input interpretation
hydrogen + red phosphorus ⟶ phosphine
Balanced equation
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 P: H: | 2 c_1 = 3 c_3 P: | 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 3/2 c_2 = 1 c_3 = 1 Multiply by the least common denominator, 2, to eliminate fractional coefficients: c_1 = 3 c_2 = 2 c_3 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 + 2 ⟶ 2
Structures
+ ⟶
Names
hydrogen + red phosphorus ⟶ phosphine
Reaction thermodynamics
Enthalpy
| hydrogen | red phosphorus | phosphine molecular enthalpy | 0 kJ/mol | -17.6 kJ/mol | 5.4 kJ/mol total enthalpy | 0 kJ/mol | -35.2 kJ/mol | 10.8 kJ/mol | H_initial = -35.2 kJ/mol | | H_final = 10.8 kJ/mol ΔH_rxn^0 | 10.8 kJ/mol - -35.2 kJ/mol = 46 kJ/mol (endothermic) | |
Entropy
| hydrogen | red phosphorus | phosphine molecular entropy | 115 J/(mol K) | 22.8 J/(mol K) | 210 J/(mol K) total entropy | 345 J/(mol K) | 45.6 J/(mol K) | 420 J/(mol K) | S_initial = 390.6 J/(mol K) | | S_final = 420 J/(mol K) ΔS_rxn^0 | 420 J/(mol K) - 390.6 J/(mol K) = 29.4 J/(mol K) (endoentropic) | |
Chemical names and formulas
| hydrogen | red phosphorus | phosphine Hill formula | H_2 | P | H_3P name | hydrogen | red phosphorus | phosphine IUPAC name | molecular hydrogen | phosphorus | phosphine
Substance properties
| hydrogen | red phosphorus | phosphine molar mass | 2.016 g/mol | 30.973761998 g/mol | 33.998 g/mol phase | gas (at STP) | solid (at STP) | gas (at STP) melting point | -259.2 °C | 579.2 °C | -132.8 °C boiling point | -252.8 °C | | -87.5 °C density | 8.99×10^-5 g/cm^3 (at 0 °C) | 2.16 g/cm^3 | 0.00139 g/cm^3 (at 25 °C) solubility in water | | insoluble | slightly soluble dynamic viscosity | 8.9×10^-6 Pa s (at 25 °C) | 7.6×10^-4 Pa s (at 20.2 °C) | 1.1×10^-5 Pa s (at 0 °C) odor | odorless | |
Units
