HBr + H2SeO4 = H2O + Br2 + H2SeO3

HBr hydrogen bromide + H_2SeO_4 selenic acid ⟶ H_2O water + Br_2 bromine + H_2SeO_3 selenious acid

Balance the chemical equation algebraically: HBr + H_2SeO_4 ⟶ H_2O + Br_2 + H_2SeO_3 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 HBr + c_2 H_2SeO_4 ⟶ c_3 H_2O + c_4 Br_2 + c_5 H_2SeO_3 Set the number of atoms in the reactants equal to the number of atoms in the products for Br, H, O and Se: Br: | c_1 = 2 c_4 H: | c_1 + 2 c_2 = 2 c_3 + 2 c_5 O: | 4 c_2 = c_3 + 3 c_5 Se: | c_2 = c_5 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 2 c_2 = 1 c_3 = 1 c_4 = 1 c_5 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 HBr + H_2SeO_4 ⟶ H_2O + Br_2 + H_2SeO_3

+ ⟶ + +

hydrogen bromide + selenic acid ⟶ water + bromine + selenious acid

Construct the equilibrium constant, K, expression for: HBr + H_2SeO_4 ⟶ H_2O + Br_2 + H_2SeO_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: 2 HBr + H_2SeO_4 ⟶ H_2O + Br_2 + H_2SeO_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 HBr | 2 | -2 H_2SeO_4 | 1 | -1 H_2O | 1 | 1 Br_2 | 1 | 1 H_2SeO_3 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression HBr | 2 | -2 | ([HBr])^(-2) H_2SeO_4 | 1 | -1 | ([H2SeO4])^(-1) H_2O | 1 | 1 | [H2O] Br_2 | 1 | 1 | [Br2] H_2SeO_3 | 1 | 1 | [H2SeO3] 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 = ([HBr])^(-2) ([H2SeO4])^(-1) [H2O] [Br2] [H2SeO3] = ([H2O] [Br2] [H2SeO3])/(([HBr])^2 [H2SeO4])

Construct the rate of reaction expression for: HBr + H_2SeO_4 ⟶ H_2O + Br_2 + H_2SeO_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: 2 HBr + H_2SeO_4 ⟶ H_2O + Br_2 + H_2SeO_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 HBr | 2 | -2 H_2SeO_4 | 1 | -1 H_2O | 1 | 1 Br_2 | 1 | 1 H_2SeO_3 | 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 HBr | 2 | -2 | -1/2 (Δ[HBr])/(Δt) H_2SeO_4 | 1 | -1 | -(Δ[H2SeO4])/(Δt) H_2O | 1 | 1 | (Δ[H2O])/(Δt) Br_2 | 1 | 1 | (Δ[Br2])/(Δt) H_2SeO_3 | 1 | 1 | (Δ[H2SeO3])/(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 = -1/2 (Δ[HBr])/(Δt) = -(Δ[H2SeO4])/(Δt) = (Δ[H2O])/(Δt) = (Δ[Br2])/(Δt) = (Δ[H2SeO3])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| hydrogen bromide | selenic acid | water | bromine | selenious acid formula | HBr | H_2SeO_4 | H_2O | Br_2 | H_2SeO_3 Hill formula | BrH | H_2O_4Se | H_2O | Br_2 | H_2O_3Se name | hydrogen bromide | selenic acid | water | bromine | selenious acid IUPAC name | hydrogen bromide | selenic acid | water | molecular bromine | selenous acid

| hydrogen bromide | selenic acid | water | bromine | selenious acid molar mass | 80.912 g/mol | 144.98 g/mol | 18.015 g/mol | 159.81 g/mol | 128.98 g/mol phase | gas (at STP) | | liquid (at STP) | liquid (at STP) | solid (at STP) melting point | -86.8 °C | | 0 °C | -7.2 °C | 70 °C boiling point | -66.38 °C | | 99.9839 °C | 58.8 °C | 315 °C density | 0.003307 g/cm^3 (at 25 °C) | 2.511 g/cm^3 | 1 g/cm^3 | 3.119 g/cm^3 | 3.004 g/cm^3 solubility in water | miscible | | | insoluble | surface tension | 0.0271 N/m | | 0.0728 N/m | 0.0409 N/m | dynamic viscosity | 8.4×10^-4 Pa s (at -75 °C) | | 8.9×10^-4 Pa s (at 25 °C) | 9.44×10^-4 Pa s (at 25 °C) | odor | | | odorless | |