CuO + CH3OH = H2O + Cu + CH2O

CuO cupric oxide + CH_3OH methanol ⟶ H_2O water + Cu copper + HCHO formaldehyde

Balance the chemical equation algebraically: CuO + CH_3OH ⟶ H_2O + Cu + HCHO Add stoichiometric coefficients, c_i, to the reactants and products: c_1 CuO + c_2 CH_3OH ⟶ c_3 H_2O + c_4 Cu + c_5 HCHO Set the number of atoms in the reactants equal to the number of atoms in the products for Cu, O, C and H: Cu: | c_1 = c_4 O: | c_1 + c_2 = c_3 + c_5 C: | c_2 = c_5 H: | 4 c_2 = 2 c_3 + 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_1 = 1 and solve the system of equations for the remaining coefficients: c_1 = 1 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: | | CuO + CH_3OH ⟶ H_2O + Cu + HCHO

+ ⟶ + +

cupric oxide + methanol ⟶ water + copper + formaldehyde

| cupric oxide | methanol | water | copper | formaldehyde molecular enthalpy | -157.3 kJ/mol | -238.7 kJ/mol | -285.8 kJ/mol | 0 kJ/mol | -108.6 kJ/mol total enthalpy | -157.3 kJ/mol | -238.7 kJ/mol | -285.8 kJ/mol | 0 kJ/mol | -108.6 kJ/mol | H_initial = -396 kJ/mol | | H_final = -394.4 kJ/mol | | ΔH_rxn^0 | -394.4 kJ/mol - -396 kJ/mol = 1.53 kJ/mol (endothermic) | | | |

Construct the equilibrium constant, K, expression for: CuO + CH_3OH ⟶ H_2O + Cu + HCHO 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: CuO + CH_3OH ⟶ H_2O + Cu + HCHO 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 CuO | 1 | -1 CH_3OH | 1 | -1 H_2O | 1 | 1 Cu | 1 | 1 HCHO | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression CuO | 1 | -1 | ([CuO])^(-1) CH_3OH | 1 | -1 | ([CH3OH])^(-1) H_2O | 1 | 1 | [H2O] Cu | 1 | 1 | [Cu] HCHO | 1 | 1 | [HCHO] 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 = ([CuO])^(-1) ([CH3OH])^(-1) [H2O] [Cu] [HCHO] = ([H2O] [Cu] [HCHO])/([CuO] [CH3OH])

Construct the rate of reaction expression for: CuO + CH_3OH ⟶ H_2O + Cu + HCHO 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: CuO + CH_3OH ⟶ H_2O + Cu + HCHO 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 CuO | 1 | -1 CH_3OH | 1 | -1 H_2O | 1 | 1 Cu | 1 | 1 HCHO | 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 CuO | 1 | -1 | -(Δ[CuO])/(Δt) CH_3OH | 1 | -1 | -(Δ[CH3OH])/(Δt) H_2O | 1 | 1 | (Δ[H2O])/(Δt) Cu | 1 | 1 | (Δ[Cu])/(Δt) HCHO | 1 | 1 | (Δ[HCHO])/(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[CuO])/(Δt) = -(Δ[CH3OH])/(Δt) = (Δ[H2O])/(Δt) = (Δ[Cu])/(Δt) = (Δ[HCHO])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| cupric oxide | methanol | water | copper | formaldehyde formula | CuO | CH_3OH | H_2O | Cu | HCHO Hill formula | CuO | CH_4O | H_2O | Cu | CH_2O name | cupric oxide | methanol | water | copper | formaldehyde