CaSO4 = O2 + SO2 + CaO

CaSO_4 calcium sulfate ⟶ O_2 oxygen + SO_2 sulfur dioxide + CaO lime

Balance the chemical equation algebraically: CaSO_4 ⟶ O_2 + SO_2 + CaO Add stoichiometric coefficients, c_i, to the reactants and products: c_1 CaSO_4 ⟶ c_2 O_2 + c_3 SO_2 + c_4 CaO Set the number of atoms in the reactants equal to the number of atoms in the products for Ca, O and S: Ca: | c_1 = c_4 O: | 4 c_1 = 2 c_2 + 2 c_3 + c_4 S: | c_1 = 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 = 2 c_2 = 1 c_3 = 2 c_4 = 2 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | 2 CaSO_4 ⟶ O_2 + 2 SO_2 + 2 CaO

⟶ + +

calcium sulfate ⟶ oxygen + sulfur dioxide + lime

Construct the equilibrium constant, K, expression for: CaSO_4 ⟶ O_2 + SO_2 + CaO 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 CaSO_4 ⟶ O_2 + 2 SO_2 + 2 CaO 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 CaSO_4 | 2 | -2 O_2 | 1 | 1 SO_2 | 2 | 2 CaO | 2 | 2 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression CaSO_4 | 2 | -2 | ([CaSO4])^(-2) O_2 | 1 | 1 | [O2] SO_2 | 2 | 2 | ([SO2])^2 CaO | 2 | 2 | ([CaO])^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 = ([CaSO4])^(-2) [O2] ([SO2])^2 ([CaO])^2 = ([O2] ([SO2])^2 ([CaO])^2)/([CaSO4])^2

Construct the rate of reaction expression for: CaSO_4 ⟶ O_2 + SO_2 + CaO 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 CaSO_4 ⟶ O_2 + 2 SO_2 + 2 CaO 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 CaSO_4 | 2 | -2 O_2 | 1 | 1 SO_2 | 2 | 2 CaO | 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 CaSO_4 | 2 | -2 | -1/2 (Δ[CaSO4])/(Δt) O_2 | 1 | 1 | (Δ[O2])/(Δt) SO_2 | 2 | 2 | 1/2 (Δ[SO2])/(Δt) CaO | 2 | 2 | 1/2 (Δ[CaO])/(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[CaSO4])/(Δt) = (Δ[O2])/(Δt) = 1/2 (Δ[SO2])/(Δt) = 1/2 (Δ[CaO])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| calcium sulfate | oxygen | sulfur dioxide | lime formula | CaSO_4 | O_2 | SO_2 | CaO Hill formula | CaO_4S | O_2 | O_2S | CaO name | calcium sulfate | oxygen | sulfur dioxide | lime IUPAC name | calcium sulfate | molecular oxygen | sulfur dioxide |

| calcium sulfate | oxygen | sulfur dioxide | lime molar mass | 136.13 g/mol | 31.998 g/mol | 64.06 g/mol | 56.077 g/mol phase | | gas (at STP) | gas (at STP) | solid (at STP) melting point | | -218 °C | -73 °C | 2580 °C boiling point | | -183 °C | -10 °C | 2850 °C density | | 0.001429 g/cm^3 (at 0 °C) | 0.002619 g/cm^3 (at 25 °C) | 3.3 g/cm^3 solubility in water | slightly soluble | | | reacts surface tension | | 0.01347 N/m | 0.02859 N/m | dynamic viscosity | | 2.055×10^-5 Pa s (at 25 °C) | 1.282×10^-5 Pa s (at 25 °C) | odor | odorless | odorless | |