Question

phase changes (graph: temperature vs energy added, y-axis: -25, 0, 25, 50, 75, 100, 125; x-axis: energy added). part d: what state would the substance be in at 75°c? options: a solid, b boiling, c freezing, d melting, e condensation, f gas, g liquid. part e: what is the melting point of the substance? options: a 100 c, b 0 c, c -25 c, d 75 c.

Explanation:

Part D

To determine the state at 75°C, analyze the phase change graph. The graph shows temperature vs. energy added. After melting (at 0°C, segment 4), the temperature rises (segment 3) until boiling at 100°C (segment 2). At 75°C, the substance is between melting (0°C) and boiling (100°C), so it's liquid. Options like solid (below melting), gas (above boiling), or phase change processes (boiling, freezing, melting, condensation) don't apply here.

The melting point is the temperature where a substance changes from solid to liquid (melting) or liquid to solid (freezing), shown as a horizontal segment on the phase change graph (constant temperature during phase change). In the graph, segment 4 is horizontal at 0°C, indicating melting (or freezing) occurs here. So the melting point is 0°C.

Answer:

G. Liquid

Part E