Question

The specific heat capacity of water is \[4.2\text{ J }{{\text{g}}^{-1}}{{\text{C}}^{-1}}\]. What does this statement mean?

Answer 1

Hint: The specific heat capacity (\[c\]) is a property of a material. Different materials have different values. It is a constant term and its meaning can be understood from the unit of the specific heat capacity.
Joule is the unit of energy/heat of a substance. g is the unit of mass of a substance and C is the unit of temperature.

Complete step by step answer:
The energy required to raise the temperature of one unit of mass of a substance to increase the temperature by unity is called the specific heat capacity of the substance.
The specific heat capacity of water is \[4.2\text{ J }{{\text{g}}^{-1}}{{\text{C}}^{-1}}\]. This statement means that 1 g of water requires 4.2 J (Joules) energy in the form of heat to raise its temperature by \[{{\text{1}}^{\text{o}}}\text{C}\].
The specific heat capacity is an intensive property. Its magnitude does not depend on the mass of the substance present.
Water has the highest heat capacity of all the liquids because water is electronegative, having two hydrogen atoms and an oxygen atom. It has a weak hydrogen bonding, hence requires higher energy to heat it than others.
We know that 1cal = 4.2 J (cal is another unit of energy)
So, in other words, we can say that the specific heat capacity of water is 1\[\text{cal }{{\text{g}}^{-1}}{{\text{C}}^{-1}}\].

Note: The specific heat capacity of material at constant pressure is denoted by \[{{c}_{p}}\]and \[{{c}_{v}}\] at constant volume.
High specific heat capacity value of water plays an important role. Water covers almost 70% of the earth’s surface and due to its high specific heat capacity, it can absorb a large amount of heat without a significant rise in the temperature.