Physics · Thermal Properties Of Matter · NEET
In SI units it is per kilogram. Specific heat capacity is heat per unit mass, and the SI unit of mass is the kilogram. So the unit is J kg^-1 K^-1. In older books you may see cal g^-1 C^-1 (calorie per gram), but for NEET always use the SI form J/kg/K. For water, s = 4180 J/kg/K, which is the same as 4.18 J/g/K or 1 cal/g/C.
Heat capacity (S) is for the whole object: S = Q/dT, unit J/K. It depends on how much matter is present. Specific heat capacity (s) is per unit mass: s = S/m = Q/(m x dT), unit J/kg/K. It is a property of the material only, not the size of the object. Two blocks of copper have different heat capacities but the same specific heat capacity.
No. Specific heat capacity is a property of the substance itself. It does not change if you take more or less of the material. What changes with mass is the total heat capacity S = m x s. If you double the mass, S doubles but s stays the same. It does depend on the nature of the substance and (slightly) on temperature.
Water has a very high specific heat capacity (4180 J/kg/K), one of the highest of common substances. So a large amount of heat is needed to change its temperature even a little. This is why water is used as a coolant in car radiators and in hot water bags, and why sea breezes have a cooling effect - land heats up faster than the sea.
Both are correct - they use different units. In SI units it is 4180 J/kg/K (often written 4.18 x 10^3 J/kg/K). If you use grams, it is 4.18 J/g/K. In calories it is about 1 cal/g/C. For NEET numericals, use 4180 or 4200 J/kg/K unless the question gives another value.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
It is the heat required to raise the temperature of 1 kg of a substance by 1 K, given by s = Q/(m x dT).
Joule per kilogram per kelvin, written J kg^-1 K^-1 (same as J kg^-1 C^-1 for temperature differences).
About 4180 J/kg/K (or 4.18 x 10^3 J/kg/K), which is unusually high compared with most substances.
It is a scalar quantity. It only has magnitude, since heat and temperature change are scalars.
Specific heat capacity is per unit mass (J/kg/K); molar heat capacity is per mole (J/mol/K). Molar = specific x molar mass.
