Br2 + NaClO3 = Cl2 + NaBrO3

Br_2 bromine + NaClO_3 sodium chlorate ⟶ Cl_2 chlorine + NaBrO_3 sodium bromate

Balance the chemical equation algebraically: Br_2 + NaClO_3 ⟶ Cl_2 + NaBrO_3 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Br_2 + c_2 NaClO_3 ⟶ c_3 Cl_2 + c_4 NaBrO_3 Set the number of atoms in the reactants equal to the number of atoms in the products for Br, Cl, Na and O: Br: | 2 c_1 = c_4 Cl: | c_2 = 2 c_3 Na: | c_2 = c_4 O: | 3 c_2 = 3 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 = 2 c_3 = 1 c_4 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | Br_2 + 2 NaClO_3 ⟶ Cl_2 + 2 NaBrO_3

+ ⟶ +

bromine + sodium chlorate ⟶ chlorine + sodium bromate

Construct the equilibrium constant, K, expression for: Br_2 + NaClO_3 ⟶ Cl_2 + NaBrO_3 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 + 2 NaClO_3 ⟶ Cl_2 + 2 NaBrO_3 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 NaClO_3 | 2 | -2 Cl_2 | 1 | 1 NaBrO_3 | 2 | 2 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) NaClO_3 | 2 | -2 | ([NaClO3])^(-2) Cl_2 | 1 | 1 | [Cl2] NaBrO_3 | 2 | 2 | ([NaBrO3])^2 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) ([NaClO3])^(-2) [Cl2] ([NaBrO3])^2 = ([Cl2] ([NaBrO3])^2)/([Br2] ([NaClO3])^2)

Construct the rate of reaction expression for: Br_2 + NaClO_3 ⟶ Cl_2 + NaBrO_3 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 + 2 NaClO_3 ⟶ Cl_2 + 2 NaBrO_3 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 NaClO_3 | 2 | -2 Cl_2 | 1 | 1 NaBrO_3 | 2 | 2 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) NaClO_3 | 2 | -2 | -1/2 (Δ[NaClO3])/(Δt) Cl_2 | 1 | 1 | (Δ[Cl2])/(Δt) NaBrO_3 | 2 | 2 | 1/2 (Δ[NaBrO3])/(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) = -1/2 (Δ[NaClO3])/(Δt) = (Δ[Cl2])/(Δt) = 1/2 (Δ[NaBrO3])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| bromine | sodium chlorate | chlorine | sodium bromate formula | Br_2 | NaClO_3 | Cl_2 | NaBrO_3 Hill formula | Br_2 | ClNaO_3 | Cl_2 | BrNaO_3 name | bromine | sodium chlorate | chlorine | sodium bromate IUPAC name | molecular bromine | sodium chlorate | molecular chlorine | sodium bromate

| bromine | sodium chlorate | chlorine | sodium bromate molar mass | 159.81 g/mol | 106.4 g/mol | 70.9 g/mol | 150.89 g/mol phase | liquid (at STP) | liquid (at STP) | gas (at STP) | solid (at STP) melting point | -7.2 °C | | -101 °C | 381 °C boiling point | 58.8 °C | 106 °C | -34 °C | 1390 °C density | 3.119 g/cm^3 | 1.3 g/cm^3 | 0.003214 g/cm^3 (at 0 °C) | 3.339 g/cm^3 solubility in water | insoluble | very soluble | | soluble surface tension | 0.0409 N/m | | | dynamic viscosity | 9.44×10^-4 Pa s (at 25 °C) | 0.00542 Pa s (at 286 °C) | | odor | | odorless | | odorless