Specific Heat Capacity of Water: Formula, Unit & Important Questions

Specific Heat Capacity of Water is approximately 4.2 J/g°C. Thus, it takes 4.2 joules of energy to raise 1 gram of water by 1 degree Celsius. Specific Heat Capacity is the heat required to raise temperature of the unit mass of a given substance by a given amount. Units of specific heat are calories or joules per gram per Celsius degree. For example, the specific heat of water is 1 calorie (or 4.186 joules) per gram per Celsius degree.

Also Read: Kinetic Theory

Key Terms: Specific Heat Capacity, Specific Heat, Heat Capacity, Heat Capacity of Water, Specific Heat Capacity Formula, Specific Heat Table, Heat Energy

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Specific Heat of Water

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Specific Heat Capacity of Water at normal temperature and pressure is roughly 4.2 J/g^oC. This means that 1 gram of water requires 4.2 joules of energy to raise 1 degree Celsius. This ‘c’ value is fairly high. This is known as the specific heat of liquid water(1 cal/g.deg) or the specific heat capacity of liquid water.

Specific Heat of Water, c = 4.186J/g^oC

The Specific Heat of Water is relatively higher when compared to other common substances. As a result, water plays a critical role in regulating temperature.

Calorie = 4.184 joules
1 joule = 1 kilogram(m)²(s)^-2 
= 0.239005736 Calorie

Specific Heat of Water

The following are some interesting properties of specific heat capacity:

• Water has a higher specific heat capacity than sand. Hence, it stays cool longer.
• Water vapour has a higher specific heat capacity than most other materials at normal temperatures.
• At normal temperature and pressure, water vapour has a specific heat capacity (C) of about 1.9 J/g°C. 

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What is Specific Heat?

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The amount of heat energy needed to change the heat content of 1g of a substance by 1 ⁰C is termed the specific heat. The direction of heat flow is always from the hotter substance to the colder substance and this exchange occurs till both substances attain equal temperature. Thus by the law of conservation of energy, the heat lost by the initially hot substance should be equal to the initially cold substance. 

Specific Heat of Different Substances

Every substance has a different mass, and hence if the same amount of heat energy is applied to different substances, the temperature gain thus varies. This variation is due to the heat capacities of the substances. 

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What is Specific Heat Capacity?

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Heat Capacity of a substance is the total amount of heat required to raise the temperature of a mass of a substance by 1°C. Let us understand this with an easy example.

• Consider two similar substances kept close to one another. Initially, both these substances are at different temperatures.
• When brought in contact, heat energy flows from hotter to colder substances.
• Thus, by the law of conservation of energy, the colder substance temperature gradually increases.

Specific Heat Capacity Video Explanation

When the mass of the given substance is unity, we call it the specific heat capacity of the substance that is the total energy required to raise the temperature of unit mass of a substance by 1°C. Specific Heat Capacity is measured in cal g^-1(°C)^-1 or J kg^-1 K^-1.

 Also Check: Thermal Expansion

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Specific Heat Capacity Formula

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The following formula can be used to calculate specific heat capacity values:

Q = cmΔT

c = Q/(mΔT)

Where,

• c = specific heat
• Q = required heat
• m = mass in millimeters
• ΔT = Temperature change of a system

Note: When a phase change occurs, this equation does not apply because the heat added or withdrawn during the phase change has no effect on the temperature.

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Specific Heat Capacity Unit

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Specific heat capacity is the quantity of heat required to raise the temperature per unit mass. 

The formula for Specific Heat Capacity = \(\frac{Energy Required(Q)}{mass(m)\times \Delta T}\)

The S.I unit for Specific Heat Capacity is JKg^-1K^-1, whereas, the SI unit for heat capacity is J.K^-1.

Specific Heat and Temperature

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Specific Heat Table

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The specific heat capacities of some important substances at atmospheric pressure are listed in a tabular form below:

Things to Remember

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• The amount of heat that is required to raise the temperature of a gram of a substance by 1 degree Celsius is known as specific heat capacity.
• The formula of Specific Heat Capacity: c=Q/(mΔT)
• The unit of Specific heat capacity is: JK^-1.
• Water has a specific heat of c = 4.186J/g^oC.
• Water absorbs heat but without a sudden rise in its temperature. Thus, it helps us in controlling our body temperature.
• Water has such high specific heat due to hydrogen bonding between its atoms.

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