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

4 years 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