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1. What is latent heat? 2. Why does the temperature of H2O not increase when it is boiling? Explain your answer by drawing a heating/cooling curve for water. 3. Describe the difference between latent heat of fusion versus latent heat of vaporization. Which process involves energy being absorbed? 4.
The latent heat of fusion is the amount of heat needed to cause a phase change between solid and liquid. The latent heat of vaporization is the amount of heat needed to cause a phase change between liquid and gas.
Heat steam from 100 °C to 120 °C. The heat needed to change the temperature of a given substance (with no change in phase) is: q = m × c × Δ T (see previous chapter on thermochemistry). The heat needed to induce a given change in phase is given by q = n × Δ H.
The heat Q required to change the phase of a sample of mass m is given by \(\mathrm{Q=mL_f}\) (melting or freezing) and \(\mathrm{Q=mL_v}\) (evaporating or condensing), where \(\mathrm{L_f}\) and \(\mathrm{L_v}\) are the latent heat of fusion and the latent heat of vaporization, respectively.
The heat \(Q\) required to change the phase of a sample of mass \(m\) is given by \[ Q = mL_f (melting/freezing),\] \[Q = mL_v (vaporization/condensation),\] where the latent heat of fusion, \(L_f\), and latent heat of vaporization, \(L_v\), are material constants that are determined experimentally.
Heat with Phase Change Worksheet. 1) How many joules are required to heat 250 grams of liquid water from 00 to 1000 C ? 2) How many joules are required to melt 100 grams of water? 3) How many joules are required to boil 150 grams of water?
The document summarizes key concepts about phase changes of matter including the kinetic theory of matter, descriptions of the three phases of matter (solid, liquid, gas), and definitions of common phase changes (melting, freezing, evaporation, condensation, sublimation, deposition).
