The commonly cited value for the specific heat capacity of liquid water is approximately:

The commonly cited value for the specific heat capacity of liquid water is approximately:

• A. 0.24 J/g·K
• B. 2.0 J/g·K
• C. 20 J/g·K
• D. 4.19 J/g·K

Answer: (D)

Specific heat capacity tells you how much energy is needed to raise the temperature of a substance by 1 degree for each gram of material. Water has a notably high value because hydrogen bonding among water molecules stores energy as they reorient and break apart with heating, so more energy is required to increase its temperature. The commonly cited figure for liquid water is about 4.19 joules per gram per kelvin, meaning roughly 4 joules are needed to raise 1 g of water by 1 K. On a per-mole basis, this corresponds to 4.184 J/g-K × 18.015 g/mol ≈ 75 J/mol-K. The other numbers are far from this standard value, reflecting materials with much lower (or in the case of the 20 J/g-K estimate, unusually high) heat capacities.

Specific heat capacity tells you how much energy is needed to raise the temperature of a substance by 1 degree for each gram of material. Water has a notably high value because hydrogen bonding among water molecules stores energy as they reorient and break apart with heating, so more energy is required to increase its temperature. The commonly cited figure for liquid water is about 4.19 joules per gram per kelvin, meaning roughly 4 joules are needed to raise 1 g of water by 1 K. On a per-mole basis, this corresponds to 4.184 J/g-K × 18.015 g/mol ≈ 75 J/mol-K. The other numbers are far from this standard value, reflecting materials with much lower (or in the case of the 20 J/g-K estimate, unusually high) heat capacities.