Linked Questions

3
votes
1answer
1k views

Thermodynamics and equilibrium constant [duplicate]

I just wanted to make sure how we can know whether it is $K_c$ (equilibrium constant of concentrations) or $K_p$ (equilibrium constant of pressures) which "comes out" of the equation, $\Delta G^o= -RT ...
1
vote
1answer
165 views

How to calculate the Gibbs energy for the vaporisation of solid ammonia? [duplicate]

Given that $P_{\ce{NH3}}=\mathrm{10~atm}$ at $298\ \mathrm K$, calculate the $\Delta G^\circ$ of the reaction $$\ce{NH3(s) <=> NH3(g)}$$ I'll begin solving the problem... I'm using the formula ...
2
votes
0answers
48 views

Why does the pressure equilibrium constant exist? [duplicate]

Since $K_c$ can already be used for calculating the equilibrium constant for a reaction involving gases, but $K_p$ cannot be used for calculating the equilibrium constant for a reaction involving ...
47
votes
4answers
3k views

Unit of the equilibrium constant: contradiction of Bridgman's theorem?

The following equation is standard in thermodynamics: $$ \Delta G^\circ=-RT\log(K) $$ where $K$ is the equilibrium constant. In dimensional analysis, Bridgman's theorem tells us that the argument ...
4
votes
1answer
10k views

Why are Kc and Kp interchangeable in the free energy-equilibrium equation? [duplicate]

In this equation that relates Standard free energy and the equilibrium constant: $\Delta GÂș=-RT \ln K_{eq}$ My textbook (and my teacher) say both $K_p$ (constant related to pressure) and $K_c$ (...
2
votes
1answer
2k views

For homogeneous equilibrium, why are liquids and solids included in the equilibrium constant (when they aren't in heterogeneous equilibria)?

In a heterogeneous reaction (where the states are varied) we do not include liquids and solids in the equilibrium equation because their concentrations do not change. E.g. Chemguide.co.uk However, ...
3
votes
0answers
689 views

Dissociation percentages of N2O4 at different pressures using Gibbs' free energy

\begin{align} \ce{N2O4(g)&<=>2NO2(g)} & \Delta_\mathrm{r}G^\circ &= \pu{4.7 kJ mol^-1} \end{align} Knowing that the standard values for pressure and temperature are $\pu{1 bar}$...
2
votes
1answer
85 views

K in Gibbs free energy

When we write for an equilibrium that $$\Delta G^\circ = -RT \ln(K)$$ Which type of $K$ , ie is it $K_\text{concentration}, K_\text{pressure}$ or $K_{\chi}$ because all these have different numeric ...
0
votes
0answers
36 views

Equilibrium constants and

I have a few questions about this two relations: We know that: $K_p$ = $e^{\frac{-\Delta G^0}{RT}}$ $(1)$ and $K_c = K_p (RT)^{\Delta n}$ $(2)$ Ok now I'm solving this problem about solubility: The ...
1
vote
0answers
22 views

Molarity of solids and liquids in equilibrium constant expression [duplicate]

Why is the molarity of pure liquids , solids and excess solvent taken 1 in the equilibrium constant expression?