Cu + Br2 = CuBr2

Cu copper + Br_2 bromine ⟶ CuBr_2 cupric bromide

Balance the chemical equation algebraically: Cu + Br_2 ⟶ CuBr_2 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Cu + c_2 Br_2 ⟶ c_3 CuBr_2 Set the number of atoms in the reactants equal to the number of atoms in the products for Cu and Br: Cu: | c_1 = c_3 Br: | 2 c_2 = 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: | | Cu + Br_2 ⟶ CuBr_2

+ ⟶

copper + bromine ⟶ cupric bromide

| copper | bromine | cupric bromide molecular enthalpy | 0 kJ/mol | 0 kJ/mol | -141.8 kJ/mol total enthalpy | 0 kJ/mol | 0 kJ/mol | -141.8 kJ/mol | H_initial = 0 kJ/mol | | H_final = -141.8 kJ/mol ΔH_rxn^0 | -141.8 kJ/mol - 0 kJ/mol = -141.8 kJ/mol (exothermic) | |

Construct the equilibrium constant, K, expression for: Cu + Br_2 ⟶ CuBr_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: Cu + Br_2 ⟶ CuBr_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 Cu | 1 | -1 Br_2 | 1 | -1 CuBr_2 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression Cu | 1 | -1 | ([Cu])^(-1) Br_2 | 1 | -1 | ([Br2])^(-1) CuBr_2 | 1 | 1 | [CuBr2] 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 = ([Cu])^(-1) ([Br2])^(-1) [CuBr2] = ([CuBr2])/([Cu] [Br2])

Construct the rate of reaction expression for: Cu + Br_2 ⟶ CuBr_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: Cu + Br_2 ⟶ CuBr_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 Cu | 1 | -1 Br_2 | 1 | -1 CuBr_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 Cu | 1 | -1 | -(Δ[Cu])/(Δt) Br_2 | 1 | -1 | -(Δ[Br2])/(Δt) CuBr_2 | 1 | 1 | (Δ[CuBr2])/(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[Cu])/(Δt) = -(Δ[Br2])/(Δt) = (Δ[CuBr2])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| copper | bromine | cupric bromide formula | Cu | Br_2 | CuBr_2 Hill formula | Cu | Br_2 | Br_2Cu name | copper | bromine | cupric bromide IUPAC name | copper | molecular bromine | dibromocopper

| copper | bromine | cupric bromide molar mass | 63.546 g/mol | 159.81 g/mol | 223.35 g/mol phase | solid (at STP) | liquid (at STP) | solid (at STP) melting point | 1083 °C | -7.2 °C | 498 °C boiling point | 2567 °C | 58.8 °C | 900 °C density | 8.96 g/cm^3 | 3.119 g/cm^3 | 4.77 g/cm^3 solubility in water | insoluble | insoluble | very soluble surface tension | | 0.0409 N/m | dynamic viscosity | | 9.44×10^-4 Pa s (at 25 °C) | odor | odorless | |