ok so lets say i have an equilibrium reaction of like
yeah.. and its K value is 1.56M^-1.
Does this mean that it favours the exothermic (back) reaction?
Does the unit corresponding to M (molarity), whether it may be M^2, M^3, or M^-2 relate to whether or not a reaction is exo or endothermic? Or do i just look at the value of delta H..?
Because for some reason, all the exothermic reactions ive seen are like
any clarification would be great just trying to get a grip on this new unit haha
Technically, equilibrium constants are meant to be expressed using a dimensionless quantity called a chemical activity, which is for most cases numerically equal to the concentration of the aqueous species in M. That's why we normally use molar concentrations in equilibrium constants. However, equilibrium constants aren't strictly meant to have units, but whatever.
In VCE chemistry, the unit comes from the fact that the equilibrium expression has [SO3]^2 on the top but [SO2]^2 [O2] on the bottom. As concentrations are in M, this means the overall units are M^2/M^3 = M^-1. Just means more gas particles on the left than on the right.
Exo/endothermic means delta H value negative/positive. It turns out that this reaction is exothermic. Really, you're meant to give a temperature when quoting equilibrium constants as these constants change with temperature only.
Exothermicity is not a very good indication of equilibrium position; dissolution of ammonium nitrate is endothermic but you'd hardly say it's disfavoured given the solubility rules that ammonium AND nitrate ions are soluble. Dissolution of salts is generally endothermic. Think about it; that's why you dissolve more at higher temperatures.