Br2 + Ba = BaBr2

Br_2 bromine + Ba barium ⟶ BaBr_2 barium bromide

Balance the chemical equation algebraically: Br_2 + Ba ⟶ BaBr_2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Br_2 + c_2 Ba ⟶ c_3 BaBr_2 Set the number of atoms in the reactants equal to the number of atoms in the products for Br and Ba: Br: | 2 c_1 = 2 c_3 Ba: | 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: | | Br_2 + Ba ⟶ BaBr_2

+ ⟶

bromine + barium ⟶ barium bromide

| bromine | barium | barium bromide molecular enthalpy | 0 kJ/mol | 0 kJ/mol | -757.3 kJ/mol total enthalpy | 0 kJ/mol | 0 kJ/mol | -757.3 kJ/mol | H_initial = 0 kJ/mol | | H_final = -757.3 kJ/mol ΔH_rxn^0 | -757.3 kJ/mol - 0 kJ/mol = -757.3 kJ/mol (exothermic) | |

Construct the equilibrium constant, K, expression for: Br_2 + Ba ⟶ BaBr_2 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: Br_2 + Ba ⟶ BaBr_2 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 Br_2 | 1 | -1 Ba | 1 | -1 BaBr_2 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression Br_2 | 1 | -1 | ([Br2])^(-1) Ba | 1 | -1 | ([Ba])^(-1) BaBr_2 | 1 | 1 | [BaBr2] 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 = ([Br2])^(-1) ([Ba])^(-1) [BaBr2] = ([BaBr2])/([Br2] [Ba])

Construct the rate of reaction expression for: Br_2 + Ba ⟶ BaBr_2 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: Br_2 + Ba ⟶ BaBr_2 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 Br_2 | 1 | -1 Ba | 1 | -1 BaBr_2 | 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 Br_2 | 1 | -1 | -(Δ[Br2])/(Δt) Ba | 1 | -1 | -(Δ[Ba])/(Δt) BaBr_2 | 1 | 1 | (Δ[BaBr2])/(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[Br2])/(Δt) = -(Δ[Ba])/(Δt) = (Δ[BaBr2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| bromine | barium | barium bromide formula | Br_2 | Ba | BaBr_2 name | bromine | barium | barium bromide IUPAC name | molecular bromine | barium | barium(+2) cation dibromide

| bromine | barium | barium bromide molar mass | 159.81 g/mol | 137.327 g/mol | 297.13 g/mol phase | liquid (at STP) | solid (at STP) | solid (at STP) melting point | -7.2 °C | 725 °C | 860 °C boiling point | 58.8 °C | 1640 °C | 1835 °C density | 3.119 g/cm^3 | 3.6 g/cm^3 | 4.78 g/cm^3 solubility in water | insoluble | insoluble | surface tension | 0.0409 N/m | 0.224 N/m | dynamic viscosity | 9.44×10^-4 Pa s (at 25 °C) | |