Input interpretation
H_2SO_4 sulfuric acid + Mg_2Si magnesium silicide ⟶ MgSO_4 magnesium sulfate + SiH_4 silane
Balanced equation
Balance the chemical equation algebraically: H_2SO_4 + Mg_2Si ⟶ MgSO_4 + SiH_4 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 H_2SO_4 + c_2 Mg_2Si ⟶ c_3 MgSO_4 + c_4 SiH_4 Set the number of atoms in the reactants equal to the number of atoms in the products for H, O, S, Mg and Si: H: | 2 c_1 = 4 c_4 O: | 4 c_1 = 4 c_3 S: | c_1 = c_3 Mg: | 2 c_2 = c_3 Si: | 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_2 = 1 and solve the system of equations for the remaining coefficients: c_1 = 2 c_2 = 1 c_3 = 2 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 H_2SO_4 + Mg_2Si ⟶ 2 MgSO_4 + SiH_4
Structures
+ ⟶ +
Names
sulfuric acid + magnesium silicide ⟶ magnesium sulfate + silane
Equilibrium constant
Construct the equilibrium constant, K, expression for: H_2SO_4 + Mg_2Si ⟶ MgSO_4 + SiH_4 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 H_2SO_4 + Mg_2Si ⟶ 2 MgSO_4 + SiH_4 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_2SO_4 | 2 | -2 Mg_2Si | 1 | -1 MgSO_4 | 2 | 2 SiH_4 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression H_2SO_4 | 2 | -2 | ([H2SO4])^(-2) Mg_2Si | 1 | -1 | ([Mg2Si])^(-1) MgSO_4 | 2 | 2 | ([MgSO4])^2 SiH_4 | 1 | 1 | [SiH4] 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 = ([H2SO4])^(-2) ([Mg2Si])^(-1) ([MgSO4])^2 [SiH4] = (([MgSO4])^2 [SiH4])/(([H2SO4])^2 [Mg2Si])
Rate of reaction
Construct the rate of reaction expression for: H_2SO_4 + Mg_2Si ⟶ MgSO_4 + SiH_4 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 H_2SO_4 + Mg_2Si ⟶ 2 MgSO_4 + SiH_4 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_2SO_4 | 2 | -2 Mg_2Si | 1 | -1 MgSO_4 | 2 | 2 SiH_4 | 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_2SO_4 | 2 | -2 | -1/2 (Δ[H2SO4])/(Δt) Mg_2Si | 1 | -1 | -(Δ[Mg2Si])/(Δt) MgSO_4 | 2 | 2 | 1/2 (Δ[MgSO4])/(Δt) SiH_4 | 1 | 1 | (Δ[SiH4])/(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[H2SO4])/(Δt) = -(Δ[Mg2Si])/(Δt) = 1/2 (Δ[MgSO4])/(Δt) = (Δ[SiH4])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)
Chemical names and formulas
| sulfuric acid | magnesium silicide | magnesium sulfate | silane formula | H_2SO_4 | Mg_2Si | MgSO_4 | SiH_4 Hill formula | H_2O_4S | Mg_2Si | MgO_4S | H_4Si name | sulfuric acid | magnesium silicide | magnesium sulfate | silane
Substance properties
| sulfuric acid | magnesium silicide | magnesium sulfate | silane molar mass | 98.07 g/mol | 76.695 g/mol | 120.4 g/mol | 32.117 g/mol phase | liquid (at STP) | solid (at STP) | solid (at STP) | gas (at STP) melting point | 10.371 °C | 1102 °C | | -185 °C boiling point | 279.6 °C | | | -112 °C density | 1.8305 g/cm^3 | 1.94 g/cm^3 | | 0.001313 g/cm^3 (at 25 °C) solubility in water | very soluble | decomposes | soluble | surface tension | 0.0735 N/m | | | dynamic viscosity | 0.021 Pa s (at 25 °C) | | | odor | odorless | | |
Units