This reaction is spontaneous except below −22.°C but proceeds at a slower rate below 165.°C.

The statement describes a thermodynamic and kinetic behavior of a chemical reaction. In thermodynamics, a reaction is classified as spontaneous if it occurs without the input of external energy at a given set of conditions, typically represented by Gibbs free energy ($\Delta G$). When $\Delta G < 0$, the reaction is spontaneous.

The first part of your statement indicates that the reaction is spontaneous except below -22.0 \, ^\circ C . This means that at temperatures higher than -22.0 \, ^\circ C , the reaction has a negative Gibbs free energy and is therefore spontaneous.

The second part mentions that the rate of the reaction slows down below 165.0 \, ^\circ C . This suggests that while the reaction may still be spontaneous at temperatures above -22.0 \, ^\circ C , the activation energy barrier that must be overcome for the reaction to proceed might not be easily surmountable at lower temperatures, hence the reduced reaction rate.

This relationship underscores the significance of temperature not only in favoring the spontaneity of a reaction but also in influencing its kinetic behavior. In summary, a reaction can be thermodynamically favorable (spontaneous) but may still face kinetic limitations at certain temperature ranges. This duality is critical in predicting reaction behavior under varying conditions.