Input interpretation
KSCN potassium thiocyanate + Fe_2(SO_4)_3·xH_2O iron(III) sulfate hydrate ⟶ K6(SO4)3 + Fe2(SCN)6
Balanced equation
Balance the chemical equation algebraically: KSCN + Fe_2(SO_4)_3·xH_2O ⟶ K6(SO4)3 + Fe2(SCN)6 Add stoichiometric coefficients, c_i, to the reactants and products: c_1 KSCN + c_2 Fe_2(SO_4)_3·xH_2O ⟶ c_3 K6(SO4)3 + c_4 Fe2(SCN)6 Set the number of atoms in the reactants equal to the number of atoms in the products for C, K, N, S, Fe and O: C: | c_1 = 6 c_4 K: | c_1 = 6 c_3 N: | c_1 = 6 c_4 S: | c_1 + 3 c_2 = 3 c_3 + 6 c_4 Fe: | 2 c_2 = 2 c_4 O: | 12 c_2 = 12 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 = 6 c_2 = 1 c_3 = 1 c_4 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 6 KSCN + Fe_2(SO_4)_3·xH_2O ⟶ K6(SO4)3 + Fe2(SCN)6
Structures
+ ⟶ K6(SO4)3 + Fe2(SCN)6
Names
potassium thiocyanate + iron(III) sulfate hydrate ⟶ K6(SO4)3 + Fe2(SCN)6
Equilibrium constant
Construct the equilibrium constant, K, expression for: KSCN + Fe_2(SO_4)_3·xH_2O ⟶ K6(SO4)3 + Fe2(SCN)6 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: 6 KSCN + Fe_2(SO_4)_3·xH_2O ⟶ K6(SO4)3 + Fe2(SCN)6 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 KSCN | 6 | -6 Fe_2(SO_4)_3·xH_2O | 1 | -1 K6(SO4)3 | 1 | 1 Fe2(SCN)6 | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression KSCN | 6 | -6 | ([KSCN])^(-6) Fe_2(SO_4)_3·xH_2O | 1 | -1 | ([Fe2(SO4)3·xH2O])^(-1) K6(SO4)3 | 1 | 1 | [K6(SO4)3] Fe2(SCN)6 | 1 | 1 | [Fe2(SCN)6] 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 = ([KSCN])^(-6) ([Fe2(SO4)3·xH2O])^(-1) [K6(SO4)3] [Fe2(SCN)6] = ([K6(SO4)3] [Fe2(SCN)6])/(([KSCN])^6 [Fe2(SO4)3·xH2O])
Rate of reaction
Construct the rate of reaction expression for: KSCN + Fe_2(SO_4)_3·xH_2O ⟶ K6(SO4)3 + Fe2(SCN)6 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: 6 KSCN + Fe_2(SO_4)_3·xH_2O ⟶ K6(SO4)3 + Fe2(SCN)6 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 KSCN | 6 | -6 Fe_2(SO_4)_3·xH_2O | 1 | -1 K6(SO4)3 | 1 | 1 Fe2(SCN)6 | 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 KSCN | 6 | -6 | -1/6 (Δ[KSCN])/(Δt) Fe_2(SO_4)_3·xH_2O | 1 | -1 | -(Δ[Fe2(SO4)3·xH2O])/(Δt) K6(SO4)3 | 1 | 1 | (Δ[K6(SO4)3])/(Δt) Fe2(SCN)6 | 1 | 1 | (Δ[Fe2(SCN)6])/(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 = -1/6 (Δ[KSCN])/(Δt) = -(Δ[Fe2(SO4)3·xH2O])/(Δt) = (Δ[K6(SO4)3])/(Δt) = (Δ[Fe2(SCN)6])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)
Chemical names and formulas
| potassium thiocyanate | iron(III) sulfate hydrate | K6(SO4)3 | Fe2(SCN)6 formula | KSCN | Fe_2(SO_4)_3·xH_2O | K6(SO4)3 | Fe2(SCN)6 Hill formula | CKNS | Fe_2O_12S_3 | K6O12S3 | C6Fe2N6S6 name | potassium thiocyanate | iron(III) sulfate hydrate | | IUPAC name | potassium isothiocyanate | diferric trisulfate | |
Substance properties
| potassium thiocyanate | iron(III) sulfate hydrate | K6(SO4)3 | Fe2(SCN)6 molar mass | 97.18 g/mol | 399.9 g/mol | 522.8 g/mol | 460.2 g/mol density | 1 g/cm^3 | | | solubility in water | | slightly soluble | | odor | odorless | | |
Units