Input interpretation
H_2O water + Br_2 bromine + Na_2S_2O_3 sodium hyposulfite ⟶ H_2SO_4 sulfuric acid + Na_2SO_4 sodium sulfate + HBr hydrogen bromide
Balanced equation
Balance the chemical equation algebraically: H_2O + Br_2 + Na_2S_2O_3 ⟶ H_2SO_4 + Na_2SO_4 + HBr Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2O + c_2 Br_2 + c_3 Na_2S_2O_3 ⟶ c_4 H_2SO_4 + c_5 Na_2SO_4 + c_6 HBr Set the number of atoms in the reactants equal to the number of atoms in the products for H, O, Br, Na and S: H: | 2 c_1 = 2 c_4 + c_6 O: | c_1 + 3 c_3 = 4 c_4 + 4 c_5 Br: | 2 c_2 = c_6 Na: | 2 c_3 = 2 c_5 S: | 2 c_3 = c_4 + 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_3 = 1 and solve the system of equations for the remaining coefficients: c_1 = 5 c_2 = 4 c_3 = 1 c_4 = 1 c_5 = 1 c_6 = 8 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 5 H_2O + 4 Br_2 + Na_2S_2O_3 ⟶ H_2SO_4 + Na_2SO_4 + 8 HBr
Structures
+ + ⟶ + +
Names
water + bromine + sodium hyposulfite ⟶ sulfuric acid + sodium sulfate + hydrogen bromide
Equilibrium constant
Construct the equilibrium constant, K, expression for: H_2O + Br_2 + Na_2S_2O_3 ⟶ H_2SO_4 + Na_2SO_4 + HBr 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: 5 H_2O + 4 Br_2 + Na_2S_2O_3 ⟶ H_2SO_4 + Na_2SO_4 + 8 HBr 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_2O | 5 | -5 Br_2 | 4 | -4 Na_2S_2O_3 | 1 | -1 H_2SO_4 | 1 | 1 Na_2SO_4 | 1 | 1 HBr | 8 | 8 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression H_2O | 5 | -5 | ([H2O])^(-5) Br_2 | 4 | -4 | ([Br2])^(-4) Na_2S_2O_3 | 1 | -1 | ([Na2S2O3])^(-1) H_2SO_4 | 1 | 1 | [H2SO4] Na_2SO_4 | 1 | 1 | [Na2SO4] HBr | 8 | 8 | ([HBr])^8 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 = ([H2O])^(-5) ([Br2])^(-4) ([Na2S2O3])^(-1) [H2SO4] [Na2SO4] ([HBr])^8 = ([H2SO4] [Na2SO4] ([HBr])^8)/(([H2O])^5 ([Br2])^4 [Na2S2O3])
Rate of reaction
Construct the rate of reaction expression for: H_2O + Br_2 + Na_2S_2O_3 ⟶ H_2SO_4 + Na_2SO_4 + HBr 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: 5 H_2O + 4 Br_2 + Na_2S_2O_3 ⟶ H_2SO_4 + Na_2SO_4 + 8 HBr 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_2O | 5 | -5 Br_2 | 4 | -4 Na_2S_2O_3 | 1 | -1 H_2SO_4 | 1 | 1 Na_2SO_4 | 1 | 1 HBr | 8 | 8 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_2O | 5 | -5 | -1/5 (Δ[H2O])/(Δt) Br_2 | 4 | -4 | -1/4 (Δ[Br2])/(Δt) Na_2S_2O_3 | 1 | -1 | -(Δ[Na2S2O3])/(Δt) H_2SO_4 | 1 | 1 | (Δ[H2SO4])/(Δt) Na_2SO_4 | 1 | 1 | (Δ[Na2SO4])/(Δt) HBr | 8 | 8 | 1/8 (Δ[HBr])/(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 = -1/5 (Δ[H2O])/(Δt) = -1/4 (Δ[Br2])/(Δt) = -(Δ[Na2S2O3])/(Δt) = (Δ[H2SO4])/(Δt) = (Δ[Na2SO4])/(Δt) = 1/8 (Δ[HBr])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)
Chemical names and formulas
| water | bromine | sodium hyposulfite | sulfuric acid | sodium sulfate | hydrogen bromide formula | H_2O | Br_2 | Na_2S_2O_3 | H_2SO_4 | Na_2SO_4 | HBr Hill formula | H_2O | Br_2 | Na_2O_3S_2 | H_2O_4S | Na_2O_4S | BrH name | water | bromine | sodium hyposulfite | sulfuric acid | sodium sulfate | hydrogen bromide IUPAC name | water | molecular bromine | | sulfuric acid | disodium sulfate | hydrogen bromide