Equilibrium concentrations for acids

[Melody Haratian 2J]

When you’re finding equilibrium concentrations for an acid, do you always have to use Ka as its equilibrium quotient?

[Nathan Lao 2I]

I believe so. Ka stands for the "acid dissociation equilibrium constant" and will always be the concentrations of [H3O+][A-]/[HA]
(HA just represents an acid with that H proton and A- is its conjugate).

[Sahiti Annadata 3D]

Yes, the Ka is always the equilibrium quotient because you are using the Ka expression to solve for the equilibrium concentrations.

[Sandy Lin 1L]

Yes, you would have to use Ka. If you were given Kb when you are solving for an acid, make sure you use that value to find the Ka using the formula (Ka)(Kb) = 10^-14