At what temperature should you slow down your heating rate if the unknown begins to melt around 112°C?

When determining the appropriate temperature to slow down the heating rate of a substance suspected to be melting at around 112°C, it's crucial to consider the phase transition behavior of solids as they approach their melting point. Slowing down the heating rate just before reaching the melting point allows for a more accurate observation of the melting process and can lead to better measurements of the melting range, which is essential for characterizing the unknown substance.

In this case, the heating should ideally be slowed down when the temperature is close to the predicted melting point. Since the unknown begins to melt at approximately 112°C, a temperature significantly lower than this, yet close enough to ensure observation of the melting transition, should be chosen. A temperature of 92°C is indeed below the melting point and allows for plenty of room for the substance to transition without risking overshooting the melting event.

Slowing the heating rate at 92°C provides an ample buffer to monitor the melting without exceeding the target temperature too quickly, ensuring any change in phase is adequately captured. This methodology follows good laboratory practice, promoting precision and reducing the risk of an inaccurate reading caused by a too rapid increase in temperature.