Chemistry Unit 1 Homework

Classification of Substances

• HCl (aq): Mixture – homogeneous
• C11H22O11 (s): Pure substance – compound
• KBr (s): Pure substance – compound
• Soil: Mixture – heterogeneous
• Cl2 (g): Pure substance – element
• CH2(OH)2 (aq): Mixture – homogeneous
• Na (s): Pure substance – element

Identification of Pure Substance Elements

• Ocean water: Mixture
• Vanilla ice cream: Mixture
• Diamond: Pure substance – element
• Quartz crystals: Pure substance – compound

Properties of Pure Substances

• The identity of a pure substance does not change when it is melted or frozen (True).

Water vs. Milk

• Water is a pure substance due to its consistent composition (H2O).
• Milk is not a pure substance as it contains various compounds, including fats, proteins, and sugar.

Physical Properties of Silver

• High luster and reflectivity
• Excellent electrical and thermal conductivity
• Ductility and malleability

Properties of Iron Nail

• Extensive property: Mass (depends on quantity)
• Intensive property: Density (remains constant regardless of quantity)

Particle Arrangement in States of Matter

• Solid: Tightly packed particles, fixed shape and volume.
• Liquid: Loosely packed particles, fixed volume but no fixed shape.
• Gas: Widely spaced particles, neither fixed volume nor shape.

Gasoline as Vapor

• Yes, gasoline in its gaseous state can be referred to as a vapor, which indicates it exists above its boiling point at a given temperature.

Physical Change Examples

• Sharpening a pencil: A physical change that alters the shape without changing the substance.
• Dissolving sugar in water: A physical change where the sugar mixes uniformly but can be recovered.

Physical State at Room Temperature

• Oxygen: Gas
• Iron: Solid
• Mercury: Liquid

Physical Change Instances

• Oxygen cooled from -150°C to -200°C: Phase change to solid
• Iron cooled from 1600°C to 1500°C: Still remains solid, no change in phase
• Mercury heated from -130°C to -100°C: Heating within liquid state

Colorless Solid at -50°C

• Specific details are required regarding the substance in question, as several could fit this description.

Substance at 1000°C

• Additional context needed to identify which substance is liquid at this temperature.

Gas to Liquid Condensation

• A specific substance needs to be identified; common candidates may include water vapor.