Why would it not be useful to just use pure ethanol or pure ethylene glycol as an antifreeze since their normal freezing points are -114.1 C abd -12C respectively.
Using pure ethanol or pure ethylene glycol as an antifreeze may not be as effective as using a mixture of these compounds with water. Here's why:
1. Freezing Point: While pure ethanol has a much lower freezing point (-114.1°C) compared to water (0°C), it also has some drawbacks. Ethanol is highly volatile and has a lower boiling point, which means it would evaporate quickly in the engine and reduce the antifreeze's effectiveness. Additionally, using pure ethanol alone can lead to the risk of engine damage if all the water content within the coolant evaporates.
2. Corrosion Protection: Antifreeze not only prevents freezing but also provides corrosion protection to the engine. Pure ethanol or ethylene glycol may not have the same anti-corrosion properties as a properly formulated antifreeze mixture. Antifreeze solutions are carefully designed to inhibit corrosion and protect different metals, such as aluminum, brass, and copper, which are commonly found in engine components.
3. Boiling Point: Ethylene glycol, with a higher boiling point than water, can help prevent engine overheating by increasing the boiling point of coolant. Using pure ethylene glycol may improve the boiling point but will also reduce the heat transfer capacity compared to a mixture with water.
4. Cost-effectiveness: Pure ethanol or ethylene glycol can be significantly more expensive than water. Mixing them with water in the right proportions provides a cost-effective solution while maintaining the desired antifreeze and anti-corrosion properties.
In practice, automotive antifreeze/coolant solutions contain a combination of water, ethylene glycol or propylene glycol, corrosion inhibitors, and other additives. The proper mixture provides a balance between freezing and boiling point protection, corrosion prevention, heat transfer properties, and cost-effectiveness.