In: Chemistry
A chemical system within a sealed 4.5 L reaction vessel is
described by the following reversible reaction equation:
H2(g) + F2(g) ↔ 2 HF(g) (K = 30.0, at 1500 K)
1)What does the size of the equilibrium constant indicate regarding
the extent of the forward reaction?
2)If some hydrogen gas and fluorine gas is added to an empty
reaction vessel, determine the reaction quotient (the value of Q)
initially.
3) Determine the equilibrium concentration of hydrogen fluoride
gas, if 0.070 mol of hydrogen gas and 0.10 mol fluorine gas are
initially placed in the 4.5 L vessel.
Ans: H2(g) + F2(g) ↔ 2 HF(g)
1) The value of K=30. we know K = Kf/kb.
Thus the size of K indicates that the forward reaction has proceeded to 30 times more extent than the backward reaction.
2) Q = [HF]2/[H2].[F2]
initially [HF] = 0, as no HF has been prepared at the starting point.
Thus the reaction quotient Q initially is zero.
3) we know K = [HF]2/[H2].[F2]
H2(g) + F2(g) ↔ 2 HF(g)
initial mole: 0.07 0.1 0
equilibrium mole: 0.07-x/2 0.1-x/2 x
Then 30 = x2 / (0.07-x/2).( 0.1-x/2) solving this we get x=0.12
then conc. of HF= n/V = 0.12mol/4.5L = 0.0267M
Thus the equillibrium concentration of HF is 0.0267M.