Question

You are in restaurant waiting for your friend and ordered coffee. it has arrived. do you add sugar in your friend's coffee and then wait for him or do you add sugar after the arrives? explain with respect to the concept of cooling.

Answer 1

⇔ Practically, it would be right to add sugar to the coffee after the arrival of the friend.

⇔ The presence of impurities lowers (depresses) the freezing point of a liquid. This can be related to the fact the cooling ultimately leads to freezing of the liquid.

⇔ Adding of sugar, here, an impurity would fasten the process of cooling down of the coffee, here, the solution.

⇔ So, in order to keep the coffee hot/warm/maintain its temperature until the friend arrives, not adding of sugar would be right.

:)