Importance of the high specific heat capacity of water

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We will show the importance of the high specific heat capacity of water in cooling systems. Water can be used as a cooling agent in many cooling systems such in the cooling system of many engines used in vehicles.

Recall that the specific heat capacity of water is 1 cal/g°C.

However, the specific heat capacity of mineral oil is about 0.40 cal/g°C.

Both liquids can be used as cooling agents. However, let us see why water is a better cooling agent than mineral oil.

Suppose that the cooling system of an automobile can hold about 6 liters of liquid.

Suppose also that the maximum temperature a car can handle without damaging the engine is 400°C.

Using water as a cooling agent, the maximum quantity of heat can be calculated using the following formula.

Q = mcΔT

6 liters of water is equal to 6000 grams.

Q = 6000 × 1 cal/g °C × 400 °C

Q = 2,400,000 calories

To keep the engine cool, the heat in the water should never be higher than 2,400,000.

Using mineral as a cooling agent, the maximum quantity of heat can be calculated using the same formula.

Q = mcΔT

6 liters of water does not have the same mass as 6 liters of mineral oil. Therefore, it is not equal to 6000 grams since the density of mineral oil is different than water.

Mass = density × volume

The density of mineral oil is 800 kg/cubic meter

6 liters = 0.006 cubic meter

Mass of 6 liters of mineral equal to 800 × 0.006 = 4.8 kg

4.8 kg = 4800 grams

Q = 4800 × 0.40 cal/g °C × 400 °C

Q = 768,000 calories

Using mineral oil, you can clearly see that the maximum amount of heat the engine could handle is 768,000 as opposed to the full capacity of 2400000 when using water.

The only way to make mineral oil reach 2,400,000 calories is to raise the temperature to a number higher than 400 degrees Celsius. However, we cannot raise the temperature to a number higher than 400 degrees Celsius since it will damage the engine. 

Because water can tolerate much more heat than mineral oil for the same temperature, it is a better cooling agent.

The importance of the high specific heat capacity of water can also be seen in nature. Check this website to see how. 

Specific heat capacity