H2SO4 + MgCl2 = HCl + MgSO4

H_2SO_4 sulfuric acid + MgCl_2 magnesium chloride ⟶ HCl hydrogen chloride + MgSO_4 magnesium sulfate

Balance the chemical equation algebraically: H_2SO_4 + MgCl_2 ⟶ HCl + MgSO_4 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2SO_4 + c_2 MgCl_2 ⟶ c_3 HCl + c_4 MgSO_4 Set the number of atoms in the reactants equal to the number of atoms in the products for H, O, S, Cl and Mg: H: | 2 c_1 = c_3 O: | 4 c_1 = 4 c_4 S: | c_1 = c_4 Cl: | 2 c_2 = c_3 Mg: | c_2 = c_4 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 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | H_2SO_4 + MgCl_2 ⟶ 2 HCl + MgSO_4

+ ⟶ +

sulfuric acid + magnesium chloride ⟶ hydrogen chloride + magnesium sulfate

| sulfuric acid | magnesium chloride | hydrogen chloride | magnesium sulfate molecular enthalpy | -814 kJ/mol | -641.3 kJ/mol | -92.3 kJ/mol | -1285 kJ/mol total enthalpy | -814 kJ/mol | -641.3 kJ/mol | -184.6 kJ/mol | -1285 kJ/mol | H_initial = -1455 kJ/mol | | H_final = -1470 kJ/mol | ΔH_rxn^0 | -1470 kJ/mol - -1455 kJ/mol = -14.2 kJ/mol (exothermic) | | |

| sulfuric acid | magnesium chloride | hydrogen chloride | magnesium sulfate molecular free energy | -690 kJ/mol | -591.8 kJ/mol | -95.3 kJ/mol | -1171 kJ/mol total free energy | -690 kJ/mol | -591.8 kJ/mol | -190.6 kJ/mol | -1171 kJ/mol | G_initial = -1282 kJ/mol | | G_final = -1361 kJ/mol | ΔG_rxn^0 | -1361 kJ/mol - -1282 kJ/mol = -79.4 kJ/mol (exergonic) | | |

Construct the equilibrium constant, K, expression for: H_2SO_4 + MgCl_2 ⟶ HCl + MgSO_4 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: H_2SO_4 + MgCl_2 ⟶ 2 HCl + MgSO_4 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 H_2SO_4 | 1 | -1 MgCl_2 | 1 | -1 HCl | 2 | 2 MgSO_4 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression H_2SO_4 | 1 | -1 | ([H2SO4])^(-1) MgCl_2 | 1 | -1 | ([MgCl2])^(-1) HCl | 2 | 2 | ([HCl])^2 MgSO_4 | 1 | 1 | [MgSO4] 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 = ([H2SO4])^(-1) ([MgCl2])^(-1) ([HCl])^2 [MgSO4] = (([HCl])^2 [MgSO4])/([H2SO4] [MgCl2])

Construct the rate of reaction expression for: H_2SO_4 + MgCl_2 ⟶ HCl + MgSO_4 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: H_2SO_4 + MgCl_2 ⟶ 2 HCl + MgSO_4 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 H_2SO_4 | 1 | -1 MgCl_2 | 1 | -1 HCl | 2 | 2 MgSO_4 | 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 H_2SO_4 | 1 | -1 | -(Δ[H2SO4])/(Δt) MgCl_2 | 1 | -1 | -(Δ[MgCl2])/(Δt) HCl | 2 | 2 | 1/2 (Δ[HCl])/(Δt) MgSO_4 | 1 | 1 | (Δ[MgSO4])/(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[H2SO4])/(Δt) = -(Δ[MgCl2])/(Δt) = 1/2 (Δ[HCl])/(Δt) = (Δ[MgSO4])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| sulfuric acid | magnesium chloride | hydrogen chloride | magnesium sulfate formula | H_2SO_4 | MgCl_2 | HCl | MgSO_4 Hill formula | H_2O_4S | Cl_2Mg | ClH | MgO_4S name | sulfuric acid | magnesium chloride | hydrogen chloride | magnesium sulfate IUPAC name | sulfuric acid | magnesium dichloride | hydrogen chloride | magnesium sulfate

| sulfuric acid | magnesium chloride | hydrogen chloride | magnesium sulfate molar mass | 98.07 g/mol | 95.2 g/mol | 36.46 g/mol | 120.4 g/mol phase | liquid (at STP) | solid (at STP) | gas (at STP) | solid (at STP) melting point | 10.371 °C | 714 °C | -114.17 °C | boiling point | 279.6 °C | | -85 °C | density | 1.8305 g/cm^3 | 2.32 g/cm^3 | 0.00149 g/cm^3 (at 25 °C) | solubility in water | very soluble | soluble | miscible | soluble surface tension | 0.0735 N/m | | | dynamic viscosity | 0.021 Pa s (at 25 °C) | | | odor | odorless | | |