Final answer:
The energy released when 18.0 g of water freezes is calculated by multiplying the mass by the latent heat of fusion for water, yielding approximately 6 kJ.
Step-by-step explanation:
The energy released when 18.0 g of water at 0°C changes from liquid to solid can be calculated using the latent heat of fusion, which is the amount of energy required to change a substance from the solid phase to the liquid phase at its melting point or vice versa without changing its temperature. For water, the latent heat of fusion is approximately 334 J/g. Therefore, to calculate the energy released when 18.0 g of water freeze, we use the formula:
Energy (Q) = mass (m) × latent heat of fusion (L_f)
So, the calculation is:
Q = 18.0 g × 334 J/g = 6012 J
The closest answer from the given options would be b. 6 kJ (6000 J), considering significant figures and rounding.