Water is capable of carrying approximately how many times more heat than an equal volume of air?

• A. 1000
• B. 3500
• C. 5000
• D. 10000

Answer: (B)

Volumetric heat capacity explains why water can carry much more heat per unit volume than air. Water has a high density and a high specific heat capacity, so per cubic meter it stores a lot of energy for a given temperature rise. Water’s specific heat is about 4.18 kJ/kg·K, and its density is about 1000 kg/m^3, giving roughly 4.18 MJ per m^3·K. Air’s specific heat is about 1.0 kJ/kg·K with a density around 1.2 kg/m^3, giving roughly 1.2 kJ per m^3·K. The ratio is about 4,180 / 1.2 ≈ 3,500. So water can carry about 3.500 times as much heat per equal volume as air. The closest option is 3500.