Freezing Point Depression

Introduction

The phenomenon of freezing point depression discusses whenever introducing a solute to such a solvent causes a lowering of the freezing temp of the solvent.

The freezing temp of such a compound seems to be the temp where the vapour pressure of the compound during its liquid phase equals the vapour pressure of the compound within the solid phase. Whenever a non-volatile solute has been dispersed in such a pure solvent, the vapour pressure lowers as per Raoult's Law. As a result, the overall vapour pressure of such a solution would be relatively lower than those of the pure solvent. Water, for example, has a freezing point of 0℃. Moreover, when the molality of the solute increases, the freezing value of the solvent moves ahead.

Definition of Freezing Point Depression

If a product begins to freeze, the molecules become slower owing to temperature decreases., but also intermolecular forces seize control. The molecules would also organise themselves in such a sequence as well as crystallise. Vapour pressure could be used to illustrate freezing point depression. When a solute is mixed with a solvent, the solvent molecules disperse, leading to a reduction in vapour pressure owing to Raoult's law. Even though perhaps the vapour pressures of both the solid as well as liquid forms of such solution should be the same at the freezing point for the process to remain in equilibrium, dramatically reducing the vapour pressure prompts to lower the temp whereby the vapour pressures of the liquid, as well as chilled forms of such solution, becomes equal. The following formula may be used to compute freezing point depression:

$$\mathrm{\vartriangle\:T_{f}\:=\:i\:\times\:K_{f}\:\times\:molality}$$

Where, 𝛥𝑇𝑓 = Freezing point depression

𝐾𝑓 = Freezing point depression constant

i = van 't Hoff factor

The van 't Hoff factor compensates for the no. of particles released in solution by such a decomposing solute, and the 𝐾𝑓 changes with the solvent.

Freezing Point Examples

• As we sprinkle salt on an icy surface, it combines with very little water, preventing the ice from refreezing.

• The characteristic may be used to make ice cream.

• Mostly in the dairy sector, we utilise freezing point depression to estimate the exact quantity of water to add to the milk; for example, milk including an EPD greater than 0.509°C is considered pure milk.

• Alcoholic drinks, such as vodka, would not freeze in the freezer because of this attribute.

• The system is helpful in radiator fluids utilised within vehicles to keep water from freezing in colder regions.

• The method makes use of ethylene glycol as well as water.

• Animals that live in cold regions have native antifreeze compounds in their bodies, such as glycerol and sorbitol.

• This trait aids in lowering the freezing point of the water throughout their bodies, allowing them to live.

• Due to the huge freezing point depression, seawater remains unfrozen even though temperatures fall below 0°C.

Uses of Freezing Point Depression

• The freezing point depression equation is being used to determine the molar mass of particulates in a standard solution.

• This can be used to calculate the standard whereby a certain solute could disperse in a solvent.

• In freezing point depression, a study known as 'Cryoscopy' is frequently beneficial. 'Cryo' indicates cold in this context, and 'scopy' signifies watching the cold. It is dependent here on the freezing point being calculated correctly.

• It can be used in thermoanalytical methods such as Differential Scanning Calorimetry as a kind of purity analysis tool.

• Most notably, freezing point depression demonstrates that adding a solute into such a solution reduces its freezing point.

• The freezing point has been reduced regardless of if the solute, as well as solvent, is liquid, solid, as well as gaseous. It is also possible in solid-solid combinations.

• By merging Raoult's Law with the Clausius Clapeyron Equation, the expression utilised within that equation is termed Blagden's Law.

Fun Facts About Freezing Point Depression

Various organisms surviving in cold weather use the notion of freezing-point depression to create a high concentration of various chemicals. There are several instances of species that make antifreeze substances, including the rainbow smelt, an arctic-living fish that yields glycerol as well as related molecules to thrive in frozen-over waterways throughout the winter season.

Other species, like the spring peeper frog, temporarily enhance the molality of their bodily fluids under the relatively low temperature of the winter season. Simultaneously, freezing weather causes a wide-scale decomposition of hepatically stored glycogen, resulting in the discharge of enormous quantities of glucose into the circulation.

Such chemicals' production aids in lowering the freezing point of the water within their bodies. According to scientists, the freezing point rises as pressure rises. When a supercooled liquid is taken to freezing temperature, the heat of fusion is released. This immediately raises the temp towards the freezing point.

Conclusion

A substance's liquid, as well as solid phases, share the same vapour pressure during freezing point depression. The solution's freezing temperature seems to be lower than those of the pure solvent. To solidify, a solution must be lowered to a temperature lower than one of its pure solvents.

The decline of a solution's freezing point would be a colligative property. It is determined by the no. of solute molecules in the solution. As a result, the more ions are there in a solution, the larger the proportions of freezing point depression. The Clausius-Clapeyron equation as well as Raoult's law could be used to compute freezing point depression. There are several intriguing and practical uses for freezing point depression.

FAQs

1. Is it possible to have a negative 𝜟𝑻𝒇?

The freezing point depression would be defined as the freezing point changes proportionally to the concentration of solutes. The difference in freezing point is stated as $\mathrm{\vartriangle\:T_{f}\:=\:T_{f,solvent}\:-\:T_{f,solvent}}$. Even though the temp of the solution might be lower than those of the pure solvent, 𝛥𝑇𝑓 becomes negative.

2. Why does the freezing point of water fall as contaminants increase?

Because the concentration of the solution increases with the existence of contaminants, the vapour pressure of such solution decreases. As a result, ice melts quickly at lower temperatures.

3. Which has the coldest temperature?

Even though it would not initiate breakdown to boost the number of particles, the 1M glucose solution seems to have the greatest freezing point.

4. Who was the first to find freezing point depression?

Raoult began teaching at the University of Grenoble in 1867 and even remained a professor there till his death in 1870. He found around 1886 that now the freezing point of such an aqueous solution decreases in ratio to the quantity of a non-electrolytic component present.

5. How is purity determined by freezing point depression?

When the 𝐾𝑓 is determined, the molal concentration of solute may be calculated from such an observed freezing point depression, providing the content is dilute enough to have been called an ideal solution.