Na + HZn = H2 + Na2Zn

Na sodium + HZn ⟶ H_2 hydrogen + Na2Zn

Balance the chemical equation algebraically: Na + HZn ⟶ H_2 + Na2Zn Add stoichiometric coefficients, c_i, to the reactants and products: c_1 Na + c_2 HZn ⟶ c_3 H_2 + c_4 Na2Zn Set the number of atoms in the reactants equal to the number of atoms in the products for Na, H and Zn: Na: | c_1 = 2 c_4 H: | c_2 = 2 c_3 Zn: | c_2 = 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_3 = 1 and solve the system of equations for the remaining coefficients: c_1 = 4 c_2 = 2 c_3 = 1 c_4 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 4 Na + 2 HZn ⟶ H_2 + 2 Na2Zn

+ HZn ⟶ + Na2Zn

sodium + HZn ⟶ hydrogen + Na2Zn

Construct the equilibrium constant, K, expression for: Na + HZn ⟶ H_2 + Na2Zn 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: 4 Na + 2 HZn ⟶ H_2 + 2 Na2Zn 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 Na | 4 | -4 HZn | 2 | -2 H_2 | 1 | 1 Na2Zn | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression Na | 4 | -4 | ([Na])^(-4) HZn | 2 | -2 | ([HZn])^(-2) H_2 | 1 | 1 | [H2] Na2Zn | 2 | 2 | ([Na2Zn])^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 = ([Na])^(-4) ([HZn])^(-2) [H2] ([Na2Zn])^2 = ([H2] ([Na2Zn])^2)/(([Na])^4 ([HZn])^2)

Construct the rate of reaction expression for: Na + HZn ⟶ H_2 + Na2Zn 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: 4 Na + 2 HZn ⟶ H_2 + 2 Na2Zn 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 Na | 4 | -4 HZn | 2 | -2 H_2 | 1 | 1 Na2Zn | 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 Na | 4 | -4 | -1/4 (Δ[Na])/(Δt) HZn | 2 | -2 | -1/2 (Δ[HZn])/(Δt) H_2 | 1 | 1 | (Δ[H2])/(Δt) Na2Zn | 2 | 2 | 1/2 (Δ[Na2Zn])/(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 = -1/4 (Δ[Na])/(Δt) = -1/2 (Δ[HZn])/(Δt) = (Δ[H2])/(Δt) = 1/2 (Δ[Na2Zn])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| sodium | HZn | hydrogen | Na2Zn formula | Na | HZn | H_2 | Na2Zn name | sodium | | hydrogen | IUPAC name | sodium | | molecular hydrogen |

| sodium | HZn | hydrogen | Na2Zn molar mass | 22.98976928 g/mol | 66.39 g/mol | 2.016 g/mol | 111.4 g/mol phase | solid (at STP) | | gas (at STP) | melting point | 97.8 °C | | -259.2 °C | boiling point | 883 °C | | -252.8 °C | density | 0.968 g/cm^3 | | 8.99×10^-5 g/cm^3 (at 0 °C) | solubility in water | decomposes | | | dynamic viscosity | 1.413×10^-5 Pa s (at 527 °C) | | 8.9×10^-6 Pa s (at 25 °C) | odor | | | odorless |