Sl unit of specific heat capacity is
J/kgK
Specific Heat Capacity: Understanding its SI Unit
The SI unit of specific heat capacity is a fundamental concept in thermodynamics, essential for understanding how materials store and transfer thermal energy. Specific heat capacity refers to the amount of heat energy required to raise the temperature of a unit mass of a substance by one degree Kelvin (or Celsius). It's a characteristic property of a material.
Specific Heat Capacity Formula and Derivation
To determine the SI unit of specific heat capacity, we first need to recall its defining formula. The heat energy ($Q$) absorbed or released by a substance is given by:
$$Q = mc\Delta T$$
Where:
- $Q$ is the amount of heat energy transferred (in Joules, J).
- $m$ is the mass of the substance (in kilograms, kg).
- $c$ is the specific heat capacity of the substance.
- $\Delta T$ is the change in temperature (in Kelvin, K).
To find the unit of $c$, we can rearrange the formula:
$$c = \frac{Q}{m\Delta T}$$
Now, let's substitute the SI units for each variable in the rearranged formula:
- Unit of $Q$ (Heat Energy) = Joule (J)
- Unit of $m$ (Mass) = kilogram (kg)
- Unit of $\Delta T$ (Change in Temperature) = Kelvin (K)
Therefore, the SI unit for specific heat capacity ($c$) is:
$$\frac{\text{J}}{\text{kg} \cdot \text{K}} \text{ or J/kgK}$$
Analysis of Options for Specific Heat Capacity Unit
Let's examine the given options based on our derivation of the specific heat capacity unit:
| Option | Unit | Analysis |
|---|---|---|
| 1 | J/mk | This unit is incorrect. 'm' typically denotes meters in physics, not mass (kg), and 'K' is for Kelvin. It does not represent specific heat capacity. |
| 2 | J/kgK | This unit directly matches our derivation of Joule per kilogram per Kelvin. This is the correct SI unit for specific heat capacity. |
| 3 | J/kg | This unit represents specific energy or specific enthalpy (energy per unit mass), not specific heat capacity, as it lacks the temperature component. |
| 4 | J/K | This unit represents heat capacity (thermal capacity), which is the heat required to raise the temperature of an entire object by one degree, without considering its mass. It is not specific heat capacity. |
Based on the detailed analysis, the correct SI unit for specific heat capacity is J/kgK.
Important Questions from The Perfect Gas
The quantity of heat required to raise the temperature of unit mass of a material by one degree centigrade is called
The amount of heat required for converting one kilogram of a solid completely into liquid is called:
The heat that must be absorbed by ice of mass 500 g at – 10°C to take it to water at 20°C is (Specific heat of Ice is 2.2 kJ/kg K, Specific heat of water is 4.2 kJ/kg K and Latent heat of fusion of ice is 300 kJ/kg)
2 kg of substance receives 500 kJ and undergoes a temperature change from 100°C to 200°C. The average specific heat of substance during the process will be
The general law for the expansion or compression of gases is:
