Sketch and label the cooling curve of a pure crystalline substance

Here is a sketch and labels for the cooling curve of a pure crystalline substance:

Temp °C | | A | / | / | / |/ T_f|------------------ B-C: Freezing (liquid and solid coexist) |
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| D +---------------------------------- Time (or Heat Removed)

• A-B: Cooling liquid. The substance is in its liquid state, and its temperature decreases as heat is removed.
• B-C: Freezing plateau. At temperature T_f (the freezing point), the substance begins to solidify. During this phase change, the temperature remains constant as latent heat of fusion is released. Both liquid and solid phases coexist.
• C-D: Cooling solid. Once all the liquid has solidified, the substance is entirely in its solid state, and its temperature continues to decrease as more heat is removed.