"Phase"

[Kassandra Molina 2B]

what does it mean for reactants and products to be in "phase"? What is a phase?

[Ryan Sydney Beyer 2B]

I assume you're just talking about the different phase states of molecules. The reactants and products could be in a gaseous phase when they are in the gaseous state. They could be in aqueous phase when dissolved and present as ions. They could be in solid phase when in a solid state but we don't include solid's in the "K" expression.

[Austin Ho 1E]

I'm not sure what context 'phase' is being referred to, but in the context of equilibrium, I think it's talking about the physical state. Since we only consider reactants and products in concentration or gas phase to contribute to the equilibrium constant, only R's & P's that are (aq) or (g) are in phase.

[Mika Sonnleitner 1A]

"In phase" refers to the physical states of the compounds in chemical equilibrium equations. However, it's important to keep in mind that the equilibrium constant does not include elements in the solid or liquid phase, only aqueous or gas phases. When an element is in the aqueous phase, the equilibrium constant is calculated from the molar concentrations of each element. When an element is in the gas phase, the equilibrium constant is calculated from the partial pressures of each element.

[ZoeHahn1J]

Think state of the reactant/product, but exclude solids and liquids from K calculations.
Hope this was helpful!

[Dayanara Ruiz]

"Phase" refers to the state in which it can be found, i.e. gas. You can have a homogenous phases (same phase) or a heterogeneous phase (different phases).