Alberta Free Tutoring And Homework Help For Chemistry 30

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olu e n e , C7H8(g), is an important organic solvent and can be produced by thefollowing equilibrium equation.C7H14(g) + energy C7H8(g) + 3 H2(g)A technician placed 3.00 mol of C7H14(g) into a 1.00 L flask. The flask was then stoppered and allowed to reach equilibrium. At equilibrium, 1.20 mol of H2(g) was present in the flask.1. The value of the equilibrium constant is

11 months ago

Answered By Mandy H

To start off make an ICE (Initial, Change, Equilibrium concentrations) table for the reaction. 

mol/L | C7H14(g)  + energy --> C7H8 (g) + 3H2(g) 

I        |   3. 00     |    ~       |     0         |   0        <--3.00mol/ 1.00 L of C7H14 was placed into flask; products always start out at 0 

C        | -1. 20      |    ~       |  +1.20    | +1.20   <-- At equilibrium there is 1.20 mol H2 so there has been a change of 1.20 M (1.20 M of H2 was produced)

E        | 1.80         |    ~       |   1.20     | 1.20      <-- 3.00- 1.20 = 1.80 M of C7H14 left at equilibrium

For the equilibrium constant, remember that it is always products/ reactants of the substances that are in gaseous or aqueous state.

Keq = [C7H8] [H2]3 / [C7H14]     <-- remember that there is a coeffient of 3 for H2 (3 mols of H2 required to react) in the original equation so there is an exponent of 3 for H2 in the equilibrium constant 

Keq = [1.20] [1.20]3 / [1.80]      <-- substitue the value from the equilibrium row from your ICE table (hint: when typing in your calculator remember brackets/ BEDMAS to avoid making calculation errors) 

Keq = 1.15 <-- Don't forget your significant digits and that there are no units for the equilibrium constant