Questions and Answers
What classification applies to HCl when it is in aqueous solution?
Which of the following is a pure substance that is an element?
Which statement about the identity of pure substances is correct when they undergo phase changes?
What are the three physical states of matter and how do their particle arrangements differ?
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Which of the following describes the process of sharpening a pencil compared to dissolving sugar in water?
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At room temperature, which of the following substances is a liquid?
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What happens to mercury when it is heated from -130°C to -100°C?
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What type of physical change does oxygen undergo when cooled from -150°C to -200°C?
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Study Notes
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.
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Description
Test your understanding of pure substances and mixtures with this chemistry homework quiz. You will classify various compounds and determine which items are pure elements. Perfect for reinforcing key concepts in chemistry.
