Homework Help: Equilibrium ICE Table Question

1. May 7, 2014

Speedking96

1. The problem statement, all variables and given/known data

Keq at a given temperature is 4

2 HF (g) <--> H2 (g) + F2 (g)

A 1 Litre jar contains 0.045 moles of fluorine at equilibrium. What was the initial quantity of hydrogen fluoride in the reaction jar?

2. The attempt at a solution

I set the initial concentration of hydrogen fluoride as x, and filled in the attached ICE table.

Afterwards:

4 = (0.045)(0.045) / (x-0.09)^2

x = 0.1125 and 0.0675

Therefore, the final answer is 0.1125 M

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2. May 7, 2014

Qube

Work looks good. Watch your sig figs. 0.090 moles of HF gas disappears, not 0.09 moles. Final answer should also be limited to 2 significant figures. So the final answer is not 0.1125 M but rather 0.11 M. This is assuming that the 1 Liter measurement is an exact measurement (i.e. it doesn't just have one sig fig but is excluded from sig fig considerations in that it is an exact number).

3. May 7, 2014

Staff: Mentor

Your answer is better than the question itself. It never said you started with HF only. Not that it can be solved without this assumption.

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