Lecture Notes: State Symbols and Predicting States of Substances

Introduction

• Understanding state symbols is crucial for writing chemical equations.
• State symbols indicate the physical state of a substance at a particular temperature.

State Symbols

• Solids: Denoted by (s).
• Liquids: Denoted by (l).
• Gases: Denoted by (g).
• Aqueous (dissolved in water): Denoted by (aq).

Examples of Using State Symbols

• Sodium (Na) in water:
  • Sodium is solid at room temperature: Na(s).
  • Water is liquid: H₂O(l).
  • Sodium hydroxide (NaOH) is aqueous: NaOH(aq).
  • Hydrogen produced is a gas: H₂(g).

Predicting States of Substances at Given Temperatures

• Exams may require predicting states using provided data.
• Conceptual Tool: Use a number line to visualize temperatures and state changes.

Example Problem

• Given Data: Determine state of water, copper, and magnesium at 800°C.

Water

• Melting Point: 0°C
• Boiling Point: 100°C
• State at 800°C: Gas (H₂O(g))

Copper

• Melting Point: 1083°C
• State at 800°C: Solid (Cu(s))

Magnesium

• Melting Point: 650°C
• Boiling Point: 1117°C
• State at 800°C: Liquid (Mg(l))

Conclusion

• Understanding state symbols and using temperature data allows for accurate predictions of the state of substances.

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