HCl + PH3 = PH4Cl

HCl hydrogen chloride + PH_3 phosphine ⟶ PH_4Cl phosphonium chloride

Balance the chemical equation algebraically: HCl + PH_3 ⟶ PH_4Cl Add stoichiometric coefficients, c_i, to the reactants and products: c_1 HCl + c_2 PH_3 ⟶ c_3 PH_4Cl Set the number of atoms in the reactants equal to the number of atoms in the products for Cl, H and P: Cl: | c_1 = c_3 H: | c_1 + 3 c_2 = 4 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_1 = 1 and solve the system of equations for the remaining coefficients: c_1 = 1 c_2 = 1 c_3 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | HCl + PH_3 ⟶ PH_4Cl

+ ⟶

hydrogen chloride + phosphine ⟶ phosphonium chloride

Construct the equilibrium constant, K, expression for: HCl + PH_3 ⟶ PH_4Cl Plan: • Balance the chemical equation. • Determine the stoichiometric numbers. • Assemble the activity expression for each chemical species. • Use the activity expressions to build the equilibrium constant expression. Write the balanced chemical equation: HCl + PH_3 ⟶ PH_4Cl Assign stoichiometric numbers, ν_i, using the stoichiometric coefficients, c_i, from the balanced chemical equation in the following manner: ν_i = -c_i for reactants and ν_i = c_i for products: chemical species | c_i | ν_i HCl | 1 | -1 PH_3 | 1 | -1 PH_4Cl | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression HCl | 1 | -1 | ([HCl])^(-1) PH_3 | 1 | -1 | ([PH3])^(-1) PH_4Cl | 1 | 1 | [PH4Cl] The equilibrium constant symbol in the concentration basis is: K_c Mulitply the activity expressions to arrive at the K_c expression: Answer: | | K_c = ([HCl])^(-1) ([PH3])^(-1) [PH4Cl] = ([PH4Cl])/([HCl] [PH3])

Construct the rate of reaction expression for: HCl + PH_3 ⟶ PH_4Cl Plan: • Balance the chemical equation. • Determine the stoichiometric numbers. • Assemble the rate term for each chemical species. • Write the rate of reaction expression. Write the balanced chemical equation: HCl + PH_3 ⟶ PH_4Cl Assign stoichiometric numbers, ν_i, using the stoichiometric coefficients, c_i, from the balanced chemical equation in the following manner: ν_i = -c_i for reactants and ν_i = c_i for products: chemical species | c_i | ν_i HCl | 1 | -1 PH_3 | 1 | -1 PH_4Cl | 1 | 1 The rate term for each chemical species, B_i, is 1/ν_i(Δ[B_i])/(Δt) where [B_i] is the amount concentration and t is time: chemical species | c_i | ν_i | rate term HCl | 1 | -1 | -(Δ[HCl])/(Δt) PH_3 | 1 | -1 | -(Δ[PH3])/(Δt) PH_4Cl | 1 | 1 | (Δ[PH4Cl])/(Δt) (for infinitesimal rate of change, replace Δ with d) Set the rate terms equal to each other to arrive at the rate expression: Answer: | | rate = -(Δ[HCl])/(Δt) = -(Δ[PH3])/(Δt) = (Δ[PH4Cl])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen chloride | phosphine | phosphonium chloride formula | HCl | PH_3 | PH_4Cl Hill formula | ClH | H_3P | ClH_4P name | hydrogen chloride | phosphine | phosphonium chloride

| hydrogen chloride | phosphine | phosphonium chloride molar mass | 36.46 g/mol | 33.998 g/mol | 70.46 g/mol phase | gas (at STP) | gas (at STP) | melting point | -114.17 °C | -132.8 °C | boiling point | -85 °C | -87.5 °C | density | 0.00149 g/cm^3 (at 25 °C) | 0.00139 g/cm^3 (at 25 °C) | solubility in water | miscible | slightly soluble | reacts dynamic viscosity | | 1.1×10^-5 Pa s (at 0 °C) |