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Example: If the equilibrium concentrations of
Cl2 and COCl2 are the same at 395°C, find the
equilibrium concentration of CO in the
reaction:
CO(g) + Cl2(g) ⇌ COCl2(g)
Keq = 1.2 × 103 at 395°C
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When we reverse the equation for a chemical
reaction for which the equilibrium constant is
Keq, we invert the equilibrium constant. That
is, the reverse reaction has the equilibrium
constant 1/Keq.
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Example: If the equilibrium concentrations of Cl2
and COCl2 are the same, and the equilibrium
constant is:
CO(g) + Cl2(g) ⇌COCl2(g)
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Keq = 1.2 × 103 at 395°C
What is the value of Keq at 395°C for the reaction
COCl2(g) ⇌ CO(g) + Cl2(g) (The reverse reaction)?
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When the coefficients of an equation are
multiplied by a common factor n to produce a
new equation, we raise the original Keq value
to the power n to obtain the new equilibrium
constant.
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Example: If the equilibrium concentrations of Cl2 and COCl2 are the same,
and the equilibrium constant is:
CO(g) + Cl2(g) ⇌COCl2(g)
Keq = 1.2 × 103 at 395°C
What is the value of Keq at 395°C for the reaction 2 CO(g) + 2 Cl2(g) ⇌2
COCl2(g) (double rxn)?
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Example: Solid ammonium carbamate, NH4CO2NH2, decomposes as
shown below:
NH4CO2NH2(s) ⇌ 2 NH3(g) + CO2(g)
At 40°C the equilibrium concentration of CO2 is 4.70 x 10-3M.
Calculate the Keq at this temperature.
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Example: The white solid salt, ammonium chloride, decomposes on
heating to form gaseous hydrogen chloride and ammonia.
NH4Cl(s) ⇌ NH3(g) + HCl(g)
At 400 K, the Keq = 6.0 × 10-9. Calculate the equilibrium
concentration of each gas at this temperature.
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See Calculations using Keq Assign