Consider ice (solid water) melting into liquid water. At 0 degrees Celsius (32 degrees Fahrenheit), the ice undergoes a phase transition and becomes water.
Daily Life Examples
Substance | Melting Point (Approximate) | Daily Life Examples |
|---|---|---|
| Ice (Water) | 0 °C (32 °F) | Ice melting into water when left at room temperature. |
| Butter | 32–35 °C (90–95 °F) | Butter melting on warm toast. |
| Chocolate | 34–38 °C (93–100 °F) | Chocolate melting in your hand or in hot cocoa. |
| Candle Wax | 37–82 °C (98–180 °F) | Candle wax melting when exposed to heat. |
| Lead | 327.5 °C (621.5 °F) | Lead melting for various applications. |
| Aluminum | 660.3 °C (1220.5 °F) | Melting aluminum for casting or machining. |
| Copper | 1,085 °C (1,985 °F) | Copper melting for metallurgical processes. |
| Iron | 1,538 °C (2,800 °F) | Melting iron for casting or metallurgy. |
| Silver | 961.8 °C (1,763.2 °F) | Silver melting for jewelry making. |
| Gold | 1,064 °C (1,947 °F) | Melting gold for jewelry or metalwork. |
Factors Effecting Melting Point
| Factor | Description | Examples |
|---|---|---|
| Intermolecular Forces | Stronger forces require more energy to overcome, leading to a higher melting point. | Ionic compounds like NaCl have high melting points due to strong electrostatic forces. |
| Molecular Size and Mass | Larger molecules and higher molecular masses generally result in higher melting points. | Compare melting points of methane (CH₄) and butane (C₄H₁₀); butane has a higher melting point. |
| Molecular Structure | The arrangement of atoms within a molecule affects the substance's transition from solid to liquid. | Isomers may have different melting points; e.g., n-pentane vs. isopentane. |
| Crystal Structure | The type of crystal lattice formed in the solid state influences the melting point. | Allotropes of carbon, like diamond and graphite, have different crystal structures. |
| Purity of Substance | Impurities can lower the melting point by disrupting the regular packing of particles. | Pure substances typically have a higher and sharper melting point than impure ones. |
| Pressure | Pressure can affect the melting point, especially for substances with low melting points. | Water can exist in a liquid state below 0 °C under high pressure. |
| Presence of Other Substances | The presence of other substances, like solutes, can alter the melting point. | Adding salt to ice lowers the melting point, forming a freezing-point depression solution. |
| Electron Cloud Symmetry | Symmetrical electron cloud distribution in molecules can result in higher melting points. | Hexane (C₆H₁₄) has a lower melting point compared to more symmetrical molecules like cyclohexane (C₆H₁₂). |