Question

Specific heat is the ratio of ......

• A. Heat capacity of substance to that of water
• B. Heat capacity of water to that of substance
• C. Thermal conductivity of substance to that of water
• D. Thermal potential of substance to that of water

Hint:

Because water has an exceptionally high heat capacity (\(1.0\ \text{cal/g}\cdot\ ^{\circ}\text{C}\)), the specific heat value of almost all other foods and biomaterials is a fraction less than 1.0.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Historically, specific heat is a dimensionless ratio comparing the thermal properties of a target substance to those of a standard reference substance (typically water).

Step 2: Detailed Explanation:
1. The specific heat of a substance is defined as the ratio of the heat capacity of a given mass of the substance to the heat capacity of an equal mass of pure water:
\[ C_{sp} = \frac{\text{Heat Capacity of Substance}}{\text{Heat Capacity of Water}} \]
2. In modern terms, specific heat capacity (\(c_p\)) is often expressed with units of \(\text{J/g}\cdot\ ^{\circ}\text{C}\).
Since the heat capacity of liquid water is approximately \(1\ \text{cal/g}\cdot\ ^{\circ}\text{C}\) (or \(4.184\ \text{J/g}\cdot\ ^{\circ}\text{C}\)), the specific heat ratio is numerically equivalent to the substance's heat capacity.

Step 3: Final Answer:
Specific heat is defined as the ratio of the heat capacity of a substance to that of water.