For conversion of compound A $$\to$$ B, the rate constant of the reaction was found to be $$4.6 \times 10^{-5}$$ L mol$$^{-1}$$ s$$^{-1}$$. The order of the reaction is ______.

We need to determine the order of the reaction from the units of the rate constant.

: Rate constant $$k = 4.6 \times 10^{-5}$$ L mol$$^{-1}$$ s$$^{-1}$$

Relation between units and order.

For an $$n^{th}$$ order reaction, the units of rate constant are:

$$[k] = \text{(concentration)}^{1-n} \text{time}^{-1} = \text{L}^{n-1} \text{mol}^{1-n} \text{s}^{-1}$$

Matching with given units:

The units L mol$$^{-1}$$ s$$^{-1}$$ correspond to:

$$\text{L}^{n-1} = \text{L}^1 \implies n - 1 = 1 \implies n = 2$$

The order of the reaction is $$\boxed{2}$$ (second order).