I am in an AP high school course and the teacher pulled a fast one on us by asking us what happens to K in an reversible equilibrium equation if the equation is flipped. K equations I am talking about go K=(Products)/(Reactants). The options were they take the square root of K to get the new k, triple it, or take the reciprocal. I am baffled, because I can't find it in my notes. Any help available? Thanks!

Think about it.

K = (produce)/reactants), so
(reactants)/(products) = ?? or if that isn't enough of a hint: try this.

100/25 = 4
25/100 = 0.25 = (1/4?)

You know, that is entirely obvious, I think I'm just making things too difficult by overthinking them. Thanks much for shaking me out of that stupor.

To determine what happens to the equilibrium constant (K) when the chemical equation is flipped, we need to understand how K relates to the reactants and products in the equilibrium expression.

In a reversible equilibrium equation, the equilibrium constant (K) is defined as the ratio of the concentrations (or partial pressures) of the products to the concentrations (or partial pressures) of the reactants, each raised to the power of their stoichiometric coefficients. Mathematically, it can be represented as:

K = [C]^c[D]^d / [A]^a[B]^b

Where A, B, C, and D are the reactants and products, and a, b, c, and d are the stoichiometric coefficients, respectively.

When the equation is flipped or reversed, the reactants become the products and vice versa. Thus, the new equilibrium expression will be:

K' = [A']^a'[B']^b' / [C']^c'[D']^d'

Where A', B', C', and D' are the new reactants and products after flipping the equation, and a', b', c', and d' are the corresponding stoichiometric coefficients.

Now, to answer your question specifically, let's consider the options:

1. Taking the square root of K: This does not apply in this case since flipping the equation does not involve taking the square root of K.

2. Tripling K: This option is not correct either because simply flipping the equation would not result in multiplying K by any specific factor like three.

3. Taking the reciprocal of K: This is the correct answer. When the equation is flipped, the equilibrium expression is also flipped, and the reciprocal of K is taken. Mathematically, it can be represented as:

K' = 1 / K

So, the new equilibrium constant (K') will be the reciprocal of the original equilibrium constant (K).

Remember, the value of K itself does not change with temperature or concentration changes, only the magnitude of K may change.