# Chemistry

posted by .

The following system is at equilibrium,at 699K in a 5L container.

H2(g)+I2(g)--->2HI(g) Kc = 54.9

Initially,the system had 2.50 moles of HI.What is the moles of H2 at equilibrium?

Can Dr.Bob check if my steps are correct?
My solution:

Initially,the concentrations of H2 & I2 are 0,whereas concentration of H1 is 2.50mol/5L = 0.50 mol/L .At equilibrium,the concentrations of H2 & I2 are assumed to be x,whereas concentration of HI is 0.50-2x

Using equlibrium constant equation with respect to concentration,
Kc = [HI]^2/[H2][I2]

54.9 = (0.50-2x)^2/x.x
Since 2x is assumed to be negligible,therefore the equation above further simplified to :

54.9 = (0.50)^2/x.x
x^2 = (0.50)^2/54.9
x = 0.06748 mol/L = [H2] = [12]

Therefore moles of H2 at equilibrium is
0.06748 mol/L X 5L = 0.337 mol

• Chemistry -

The set up looks good but you can't neglect the 2x. I ran through it quickly and obtained 0.266 for mols H2 by solving the quadratic.

• Chemistry -

But why I can't ignore the 2x? Could Dr.Bob please explain?

## Similar Questions

1. ### AP Chemistry

For the system 2SO2(g) + O2(g) <--> 2SO3 (g), change in enthalpy is negative for the production of SO3. At a particular temperature, 8.00 moles of sulfur dioxide and 10.00 moles of sulfur trioxide are introduced into a 2.00 L …
2. ### Chemistry

The following reaction has an equilibrium constant of 0.020 at a given temperature. 2HI(g) I2(g) + H2(g) If you have 1.00 mol HI(g) in a 0.750-L container initially, how many moles of HI(g) will be present when the system reaches equilibrium?
3. ### chemistry

The following reaction has an equilibrium constant of 0.50 at a given temperature. HCHO(g) CO(g) + H2(g) If you have 0.55 moles of HCHO(g) in a 1.0L container initially, how many moles of HCHO will be present when the system reaches …
4. ### chemistry

Initially, there are 33 moles of A and 0 moles of B. How many moles of A and B will be present after the system reaches equilibrium?
5. ### chemistry

A study of the system, H2(g) + I2(g) == 2 HI(g), was carried out. Kc = 54.9 at 699.0 K (Kelvin) for this reaction. A system was charged with 2.50 moles of HI in a 5.00 liter vessel as the only component initially. The system was brought …
6. ### Chemistry

A reaction mixture of 4.0 mL of 0.002 M SCN- and 5.0 mL of 0.002 M Fe3+ is diluted to 10.0 mL with 0.1 M HNO3 to form the blood-red FeNCS2+ complex. The equilibrium molar concentration of the FeNCS2+ determined from a standardization …
7. ### Chemistry (Equilibrium)

Consider the following equilibrium system at 900°C: H20(g) + CO(g) <==> H2(g) + CO2(g) Initially 5.0 moles of H2O and 4.0 moles of CO were reacted. At equilibrium, it is found that 2.0 moles of H2 are present. How many moles …
8. ### chemistry

Hydrogen iodide decomposes according to the reaction 2HI(g)H2(g) + I2(g) A sealed 1.50 L container initially holds .00623 moles of H2, .00414 moles of I2, and .0244 moles of HI at 703K. When equilibrium constant is reached, the concentration …
9. ### chemistry

A reaction mixture of 4.0 mL of 0.002 M SCN- and 5.0 mL of 0.002 M Fe3+ is diluted to 10.0 mL with 0.1 M HNO3 to form the blood-red FeNCS2+ complex. The equilibrium molar concentration of the FeNCS2+ determined from a standardization …
10. ### Chemistry

For the system, H2(g) + X2(g) <--> 2HX(g), Kc = 24.4 at 300 K. A system was charged with 2.00 moles of HX in a 3.00 liter container. The catalyst was introduced using a remote unit, and the system was allowed to come to equilibrium. …

More Similar Questions