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Questions and Answers
Which classification describes HCl (aq)?
Which classification describes HCl (aq)?
What type of substance is a diamond?
What type of substance is a diamond?
Which of the following is true regarding the identity of a pure substance when it is melted or frozen?
Which of the following is true regarding the identity of a pure substance when it is melted or frozen?
What is an example of an extensive property of an iron nail?
What is an example of an extensive property of an iron nail?
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Which substance is a solid at -50°C?
Which substance is a solid at -50°C?
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What happens to oxygen as it is cooled from -150°C to -200°C?
What happens to oxygen as it is cooled from -150°C to -200°C?
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Which state of matter are particles closest together?
Which state of matter are particles closest together?
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Which of the following substances condenses from a gas to a liquid as the temperature drops from 20°C to -50°C?
Which of the following substances condenses from a gas to a liquid as the temperature drops from 20°C to -50°C?
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Study Notes
Pure Substances and Mixtures
- HCl (aq): classified as a homogeneous mixture.
- C11H22O11 (s): identified as a pure substance and specifically a compound.
- KBr (s): recognized as a pure substance and a compound.
- Soil: categorized as a heterogeneous mixture.
- Cl2 (g): identified as a pure substance and an element.
- CH2(OH)2 (aq): classified as a homogeneous mixture (assuming aqueous solution).
- Na (s): recognized as a pure substance and an element.
Pure Substances - Elements and Compounds
- Diamond: is a pure substance and specifically classified as an element.
- Quartz crystals: are classified as a pure substance and specifically a compound.
- Ocean water and vanilla ice cream are not pure substances since they consist of mixtures.
Properties of Pure Substances
- A pure substance's identity remains unchanged during melting or freezing, confirming the concept of its physical state.
Water vs. Milk
- Water is a pure substance due to its uniform composition, while milk is considered a mixture because it contains suspended particles and varying components.
Physical Properties of Silver
- Common properties include shininess (luster), conductivity (thermal and electrical), and malleability (ability to be shaped).
Extensive vs. Intensive Properties
- Extensive property example: Mass of an iron nail, which varies based on the amount of iron.
- Intensive property example: Density of an iron nail, remains constant regardless of size.
Particle Arrangement in States of Matter
- Solid: particles are tightly packed in a fixed arrangement.
- Liquid: particles are close together but can move freely.
- Gas: particles are far apart and move independently.
Vapor vs. Gas
- Gasoline in gaseous form can be referred to as vapor, as vapor typically describes the gaseous state of substances that are liquid or solid at room temperature.
Physical Changes
- Sharpening a pencil involves physical change (removal of material), whereas dissolving sugar in water results in a homogeneous mixture, a different kind of physical change.
Physical States at Room Temperature
- Oxygen: gaseous state.
- Iron: solid state.
- Mercury: liquid state.
Physical Changes in Different Instances
- Cooling oxygen from -150°C to -200°C is a physical change (condensation).
- Cooling iron from 1600°C to 1500°C also accounts for a physical change (solid phase change).
- Heating mercury from -130°C to -100°C is a physical change (melting).
Substances Under Specific Conditions
- Substance that is solid at -50°C: Specific identification needed (not provided).
- Liquid at 1000°C: Specific identification needed (not provided).
- Substance that condenses from gas to liquid between 20°C to -50°C: Specific identification needed (not provided).
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Description
This homework covers classifications of substances and mixtures in chemistry, focusing on pure substances, elements, and compounds. You'll classify various examples and identify pure elements from a list. Test your understanding of chemistry fundamentals with this assignment!
