Question

A car owner who knows no chemistry has to put antifreeze in his car's radiator. The instructions recommend a mixture of \(30 \%\) ethylene glycol and \(70 \%\) water. Thinking he will improve his protection he uses pure ethylene glycol, which is a liquid at room temperature. He is saddened to find that the solution does not provide as much protection as he hoped. The pure ethylene glycol freezes solid in his radiator on a very cold day, while his neighbor, who did use the \(30 / 70\) mixture, has no problem. Suggest an explanation.

Short answer

The car owner who used pure ethylene glycol experienced freezing because the freezing point of ethylene glycol alone is not as low as that of the recommended 30% ethylene glycol and 70% water mixture. This mixture provides better protection against extreme temperatures due to the freezing point depression and raised boiling point. Following the manufacturer's recommendation for antifreeze mixtures ensures optimal performance of the car's cooling system in different temperature conditions.

Step-by-step solution

Understand the role of ethylene glycol and water in an antifreeze mixture

Ethylene glycol (C2H6O2) is a chemical compound that is commonly used as an antifreeze agent in car radiators because it has a low freezing point and high boiling point. However, when used alone, it does not work as effectively as when mixed with water. The recommended mixture of 30% ethylene glycol and 70% water not only lowers the freezing point of the solution, but it also raises the boiling point, thereby providing comprehensive protection against extreme temperatures for the car's cooling system.

Explain the freezing point depression

When a solute, like ethylene glycol, is added to a solvent, like water, their interaction affects the freezing point of the solution. This is known as freezing point depression. The freezing point of the mixture is lower than the freezing point of either ethylene glycol or water alone. This property helps to prevent the mixture from freezing under cold conditions.

Discuss the effect of using pure ethylene glycol

Using pure ethylene glycol rather than the recommended mixture does not provide as much protection because the freezing point is not as low as in the mixture with water. As a result, the pure ethylene glycol is more susceptible to freezing on a very cold day. Additionally, the boiling point of pure ethylene glycol is lower than that of the mixture, which means it could potentially boil in a hotter environment and cause overheating in the car's cooling system.

Conclude with an explanation

The reason the car owner who used pure ethylene glycol experienced freezing is that the freezing point of ethylene glycol alone is not as low as that of the recommended 30% ethylene glycol and 70% water mixture. The mixture provides better protection against extreme temperatures due to its lowered freezing point and raised boiling point. Therefore, it is always advisable to follow the manufacturer's recommendation for antifreeze mixtures to ensure the optimal performance of the car's cooling system in different temperature conditions.

Key concepts

Ethylene Glycol

Ethylene glycol is a colorless, odorless liquid that is frequently used in automotive cooling systems. It serves a critical role by lowering the freezing point of the coolant mixture, helping to protect the engine during cold weather. This compound has a relatively low freezing point by itself, which is why it's useful in winter conditions. However, it still benefits from being mixed with water. Ethylene glycol also has a high boiling point, which helps in preventing the engine from overheating during warmer days.

When used properly in an antifreeze mixture, ethylene glycol ensures that the car's cooling system remains functional under a variety of temperature conditions. Without it, the coolant could freeze in cold weather, potentially damaging engine parts. Conversely, it could evaporate if the temperature becomes too high, which is why it's an essential component of a balanced antifreeze formulation.

Antifreeze Mixture

An antifreeze mixture primarily contains ethylene glycol and water, carefully balanced to protect engines from extreme temperatures. The ideal mixture recommended by manufacturers is often 30% ethylene glycol and 70% water. This combination utilizes a concept known as "freezing point depression."

Adding ethylene glycol to water impacts the intermolecular interactions between the water molecules, effectively lowering the freezing point of the solution. This means that the coolant can remain liquid at much lower temperatures than either pure water or pure ethylene glycol alone. Additionally, this mixture raises the boiling point, providing a dual benefit by preventing both freezing and overheating under various environmental conditions.

When preparing an antifreeze mixture, it's crucial to follow the manufacturer's guidelines to ensure maximum protection and efficiency of the vehicle's cooling system. Ignoring these proportions can lead to inadequate protection and possible technical issues.

Radiator Protection

Radiator protection is vital for the smooth operation and longevity of a vehicle's engine. The radiator forms part of the cooling system, which is essential for managing the temperature of the engine. Without proper protection, the engine risks overheating in warm weather or being damaged by expanding frozen fluids in cold weather.

The antifreeze mixture plays a major role in radiator protection by stabilizing the temperature of the engine coolant. By ensuring the coolant does not freeze or boil, it safeguards the engine against potential damages caused by thermal stress. An improper mixture might lead to the engine's coolant freezing, which may cause the radiator to burst or the engine block to crack.

Overall, ensuring appropriate radiator protection involves maintaining the correct antifreeze mixture. It is not only about lowering the freezing point but also about ensuring that various components of the engine and the cooling system work effectively and harmoniously. Regular checks and maintenance of the radiator and coolant levels help in preventing issues and extend the life of the vehicle.