The heat required to raise a mass of a substance through 1K is known as

Analysis

The question asks for the definition of the amount of heat energy required to increase the temperature of a specific mass of a substance by 1 Kelvin (or 1 degree Celsius).

Concept Explanation

To understand this, we must distinguish between Heat Capacity and Specific Heat Capacity:

1. Heat Capacity ($C$): This is defined as the quantity of heat required to raise the temperature of a given mass of a substance by 1K (or 1°C). Its unit is $J/K$. • Formula: $C = mc$ (where $m$ is mass and $c$ is specific heat capacity).
2. Specific Heat Capacity ($c$): This is defined as the quantity of heat required to raise the temperature of unit mass (1kg) of a substance by 1K (or 1°C). Its unit is $J/kg \cdot K$.

Since the question specifies "a mass of a substance" (implying the total mass of the object in question) rather than "unit mass," it refers to the total heat capacity of that object.

Step-by-Step Solution

• Step 1: Identify the variables. We are looking for the heat ($Q$) required for a temperature change ($\Delta T = 1K$) for a mass ($m$).
• Step 2: Recall the relationship $Q = C \Delta T$.
• Step 3: If $\Delta T = 1K$, then $Q = C$.
• Step 4: Compare this to the options. Option A refers to "unit mass," while Option D refers to the mass of the substance as a whole. Therefore, the definition provided matches Heat Capacity.

Conclusion

This is consistent with the standard physics definition where "Heat Capacity" is the energy required to raise the temperature of the entire body by 1K, whereas "Specific Heat Capacity" is reserved for a unit mass (1kg).

Exam Tip

A simple way to remember the difference:

• Specific = 1kg (Think of "Specific" as "Specific unit mass").
• Heat Capacity = The whole object (Think of it as the "Capacity" of the whole object to hold heat).