Chemistry · Thermodynamics · NEET
It is the amount of heat you must add to raise the temperature of ONE unit of mass (1 gram or 1 kilogram) of a substance by 1 degree (1 kelvin or 1 °C). The word 'specific' means 'per unit mass'. So if water has c = 4.18 J/g/K, it takes 4.18 joules to warm just 1 gram of water by 1 degree.
Heat capacity (C) is for the WHOLE object of any mass — it is the heat to raise that entire sample by 1 degree. Specific heat capacity (c) is for exactly 1 unit of mass. They are linked by C = c·m. So heat capacity depends on how much stuff you have; specific heat does not. NCERT gives q = c·m·ΔT = C·ΔT, which shows C = c·m.
c is the specific heat capacity. In the equation q = m·c·ΔT: q is the heat added (in joules), m is the mass, c is the specific heat, and ΔT is the change in temperature (final minus initial). Rearranged, c = q / (m·ΔT). This is the most common way NEET tests specific heat.
The SI unit is joule per kilogram per kelvin (J kg⁻¹ K⁻¹). It is also commonly written as J g⁻¹ K⁻¹ (per gram) or J g⁻¹ °C⁻¹. Because a change of 1 K equals a change of 1 °C, using kelvin or celsius in the denominator gives the same number.
Specific heat capacity is an INTENSIVE property — it does not depend on how much substance you have. 1 gram of water and 1 kg of water have the same specific heat (4.18 J/g/K). But heat capacity (C = c·m) is EXTENSIVE because it grows with mass. NEET loves this distinction.
Both are 'per one unit', but the unit is different. Specific heat is per unit MASS (per 1 gram or 1 kg). Molar heat capacity (Cm) is per one MOLE. NCERT: molar heat capacity Cm = C/n is the heat to raise 1 mole by 1 degree, while specific heat is the heat to raise 1 unit mass by 1 degree. Convert using c × molar mass = Cm.
Water needs a lot of heat to change its temperature because much of the added energy goes into breaking hydrogen bonds between water molecules instead of speeding them up. A high specific heat (4.18 J/g/K) means water heats and cools slowly, which is why it is used as a coolant and why oceans stabilise climate. This is a common conceptual NEET question.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
c = q / (m·ΔT), which comes from rearranging q = c·m·ΔT. Here q is heat, m is mass, and ΔT is temperature change. NCERT writes it as q = c·m·ΔT = C·ΔT.
Joule per kilogram per kelvin (J kg⁻¹ K⁻¹). It is often also written as J g⁻¹ K⁻¹.
No. Heat capacity C is for the whole sample; specific heat c is for 1 unit of mass. They are related by C = c·m.
About 4.18 J g⁻¹ K⁻¹ (or 4184 J kg⁻¹ K⁻¹). This high value means water resists temperature change, which is important in calorimetry.
It is the base for calorimetry and for calculating heat q in reactions. Many NEET numericals give q = m·c·ΔT to find heat lost or gained, so you must know c is per unit mass and intensive.
