The Arrival of Summer and the Delight of Ice Cream

As summer sets in, the heat becomes increasingly unbearable, especially during the afternoons. With the rise in temperature, our cravings for cold treats intensify. Everyone loves indulging in ice cream during the hot months, and when laziness strikes, ice cream vendors come to our neighborhoods. The familiar sound of their bells signals their arrival, and we instantly recognize that the ice cream vendor is nearby.

The Ice Cream Vendor's Cart

The vendor typically has a cart filled with ice, where all the ice creams are stored. Surprisingly, despite the scorching heat, the ice cream remains intact and does not melt. This phenomenon occurs because the vendor keeps the ice cream in a box filled with ice. Logically, one would expect the ice to melt quickly, but it doesn't, as the vendor adds salt to the ice.

The Science of Ice and Salt

Many of you might be wondering about the relationship between ice and salt. To understand this, we need to delve into concepts like freezing point, boiling point, and depression in freezing point. These topics are often covered in school science classes, and if you've forgotten, let's refresh your memory.

The freezing point is the temperature at which a liquid turns into a solid. For instance, the freezing point of water is 0 degrees Celsius, at which it solidifies into ice. Conversely, the boiling point is the temperature at which a liquid begins to boil; for water, this is 100 degrees Celsius.

Depression in freezing point refers to the phenomenon where the freezing point of a substance decreases when a non-volatile solute is added. This addition lowers the vapor pressure of the liquid, resulting in a lower freezing point and a higher boiling point.

Why Salt Prevents Ice from Melting

In simpler terms, adding salt to ice raises its boiling point, which prevents it from melting quickly. Therefore, when the ice cream vendor mixes salt with the ice, he gains a dual advantage: the ice does not melt, and neither does the ice cream.

Interestingly, the vendor may not even be aware of the scientific principles behind this daily practice of enhancing the ice's boiling point.