H2 (g)+I2 (g)↔2HI(g)
Calculate ΔG for the system at 700 K when the concentrations are [H2] = 0.12M, [I2] = 0.27M, and [HI] = 0.118M.
What would be my first step? If I make an ICE chart, what would I do from there? I just need the first step to help me out :(
THANKS!
I assume this is not at equilibrium. If that is the case, then
dG = dGorxn + RTlnQ
dGorxn you obtain from
dGorxn = *n*dGo formation products) - (n*dGo formation reactants)
Then Q is (HI)^2/(H2)(I2)
Dr. Bob, as grateful as I am you took the time to answer my question, I do not believe you are right. In order to get Q, it needs to be in atm, and I am dealing with M?
if I am wrong, can you explain to me what I would need to do next?
Why must you use atm? You use atm for gases and when you have pressures, these aren't gases so you use molarity. Calculation of Q occurs for either. In fact, one may use, if the situation occurs, a mix where pressure is used for the gas ad molarities for the solutions. For example,
Zn(s) + 2H^+(aq) ==> Zn^2+(aq) + H2(g)
Q for that rxn is (Zn^2+)*pH2/(H^+)^2
The Zn^2+ and H^+ are substituted in M and pH2 in atm.
However, if you feel uncomfortable with this, please do seek a second opinion.
To proceed with the problem, first calculate dGorxn from the equation I provided above, substitute the concns and calculate Q, then plug that into the dGrxn = dGo + RTlnQ and solve for dGrxn Good luck.
To calculate ΔG for the given chemical reaction at 700 K, you would need to use the equation:
ΔG = ΔG° + RT ln(Q)
where ΔG is the change in Gibbs free energy, ΔG° is the standard Gibbs free energy change at the standard conditions, R is the ideal gas constant (8.314 J/(mol·K)), T is the temperature in Kelvin, ln is the natural logarithm, and Q is the reaction quotient.
The first step is to set up an ICE (Initial, Change, Equilibrium) chart. This will help organize the given concentrations and changes as the reaction progresses towards equilibrium.
For the given reaction: H2 (g) + I2 (g) ⇌ 2HI (g)
The initial concentrations are:
[H2] = 0.12 M
[I2] = 0.27 M
[HI] = 0.118 M
In the ICE chart, you would start with the initial concentrations and then determine the changes in concentration. Since the stoichiometry of the reaction is 1:1:2 (H2:I2:HI), the change in concentration for H2 will be -x, for I2 will be -x, and for HI will be +2x, where x represents the change in concentration at equilibrium.
After determining the changes in concentration, you can express them in terms of the initial concentrations. So the equilibrium concentrations will be:
[H2] = 0.12 - x
[I2] = 0.27 - x
[HI] = 0.118 + 2x
From there, you can use the equilibrium concentrations to write the expression for the reaction quotient (Q). In this case, Q = ([HI]^2) / ([H2] * [I2]).
So the first step is to set up the ICE chart and express the equilibrium concentrations in terms of variables (x in this case).