Answer to Question #166111 in General Chemistry for Phyroe

Question

Compare the advantages and disadvantages of methyl alcohol and glycerin as antifreeze substances in automobile radiators.

Answer 1

 Advantages of glycerin: Conversation in a wide temperature range from -30 to +105 ° C. Even when the substance is completely frozen, it does not expand and does not cause damage to pipes. After thawing, all its original properties are restored.

The coolant is sold ready-made and does not require additional dilution with water. Glycolic formulations must be diluted;

Antifreeze does not cause corrosion or damage to floor heating elements, including galvanized pipes and rubber gaskets;The substance is absolutely safe for human health and the environment, which is very important in the event of leaks or damage to the system as a whole;

At a relatively high price, the composition has a long term of use up to 8 years. Another type of antifreeze has been used for about 5 years;

The coolant can be poured into the pipes after any other type of antifreeze; flushing is not required;

Antifreeze is made only from high quality raw materials, which are also used in the food and cosmetic industries;

Belongs to the class of non-flammable substances.

DISADVATAGES:

 Freezing increases the density and viscosity of the glycerin composition, which leads to a decrease in its heat capacity. In a heating system project, pipes of a larger diameter will have to be used than when using ordinary water;

The high viscosity of the composition will require the installation of a more powerful circulation pump in the heating system;

Glycerin-based antifreeze requires the use of reliable and expensive gaskets and seals during the heating installation process. Teflon or paronite gaskets are recommended;

methyl alcohol:

 Methanol is the simplest monohydric alcohol that forms poisonous formaldehyde in certain reactions with water. Begins to boil at 85 ° C, binds water and "eats" aluminum. Prohibited by law for use in antifreeze. Lights up when heated.

It is impossible to use antifreeze in a concentrated form (ethylene glycol + additives): such a mixture crystallizes already at -16C and poorly removes heat from the engine components. For efficient operation, the concentrate is mixed with water - its heat capacity is 4 times higher than that of ethylene glycol.

It turns out that the higher the% of water in the antifreeze, the better it removes heat. The crystallization temperature of the liquid also changes depending on the amount of water.