H2S + KClO3 = H2O + S + KCl

Input interpretation

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H_2S (hydrogen sulfide) + KClO_3 (potassium chlorate) ⟶ H_2O (water) + S (mixed sulfur) + KCl (potassium chloride)

Balanced equation

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Balance the chemical equation algebraically: H_2S + KClO_3 ⟶ H_2O + S + KCl Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2S + c_2 KClO_3 ⟶ c_3 H_2O + c_4 S + c_5 KCl Set the number of atoms in the reactants equal to the number of atoms in the products for H, S, Cl, K and O: H: | 2 c_1 = 2 c_3 S: | c_1 = c_4 Cl: | c_2 = c_5 K: | c_2 = c_5 O: | 3 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 3 c_2 = 1 c_3 = 3 c_4 = 3 c_5 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 3 H_2S + KClO_3 ⟶ 3 H_2O + 3 S + KCl

+ ⟶ + +

Names

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hydrogen sulfide + potassium chlorate ⟶ water + mixed sulfur + potassium chloride

Equilibrium constant

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Construct the equilibrium constant, K, expression for: H_2S + KClO_3 ⟶ H_2O + S + KCl 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: 3 H_2S + KClO_3 ⟶ 3 H_2O + 3 S + KCl 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_2S | 3 | -3 KClO_3 | 1 | -1 H_2O | 3 | 3 S | 3 | 3 KCl | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression H_2S | 3 | -3 | ([H2S])^(-3) KClO_3 | 1 | -1 | ([KClO3])^(-1) H_2O | 3 | 3 | ([H2O])^3 S | 3 | 3 | ([S])^3 KCl | 1 | 1 | [KCl] 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 = ([H2S])^(-3) ([KClO3])^(-1) ([H2O])^3 ([S])^3 [KCl] = (([H2O])^3 ([S])^3 [KCl])/(([H2S])^3 [KClO3])

Rate of reaction

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Construct the rate of reaction expression for: H_2S + KClO_3 ⟶ H_2O + S + KCl 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: 3 H_2S + KClO_3 ⟶ 3 H_2O + 3 S + KCl 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_2S | 3 | -3 KClO_3 | 1 | -1 H_2O | 3 | 3 S | 3 | 3 KCl | 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 H_2S | 3 | -3 | -1/3 (Δ[H2S])/(Δt) KClO_3 | 1 | -1 | -(Δ[KClO3])/(Δt) H_2O | 3 | 3 | 1/3 (Δ[H2O])/(Δt) S | 3 | 3 | 1/3 (Δ[S])/(Δt) KCl | 1 | 1 | (Δ[KCl])/(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 = -1/3 (Δ[H2S])/(Δt) = -(Δ[KClO3])/(Δt) = 1/3 (Δ[H2O])/(Δt) = 1/3 (Δ[S])/(Δt) = (Δ[KCl])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)