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What is meant by a substance?
What is meant by a substance?
A substance is a pure form of matter that has a fixed composition and specific properties.
List the points of difference between homogeneous and heterogeneous mixtures.
List the points of difference between homogeneous and heterogeneous mixtures.
Homogeneous mixtures have a uniform composition and appearance throughout, meaning the components are evenly distributed. Heterogeneous mixtures have non-uniform composition with visibly distinct components.
What is a solution?
What is a solution?
A solution is a type of homogeneous mixture formed when one or more substances (solutes) dissolve evenly in another substance (solvent).
Which of the following are examples of solutions?
Which of the following are examples of solutions?
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What is a suspension?
What is a suspension?
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Alloys are a type of homogeneous mixture.
Alloys are a type of homogeneous mixture.
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The process of burning a candle is a physical change.
The process of burning a candle is a physical change.
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The solubility of a substance generally increases as the temperature increases.
The solubility of a substance generally increases as the temperature increases.
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What are some examples of separation techniques used to separate mixtures?
What are some examples of separation techniques used to separate mixtures?
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A compound can be broken down into simpler substances by physical means.
A compound can be broken down into simpler substances by physical means.
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Which of the following is a pure substance?
Which of the following is a pure substance?
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What are the steps involved in making tea?
What are the steps involved in making tea?
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The solubility of potassium nitrate in water decreases as temperature decreases.
The solubility of potassium nitrate in water decreases as temperature decreases.
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What is the difference between a colloid and a suspension?
What is the difference between a colloid and a suspension?
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Which of the following is a homogeneous mixture?
Which of the following is a homogeneous mixture?
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How would you confirm that a colorless liquid given to you is pure water?
How would you confirm that a colorless liquid given to you is pure water?
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Study Notes
Chapter 2: Is Matter Around Us Pure?
- Matter can be judged as pure or a mixture.
- Pure substances contain only one type of particle, with consistent properties.
- Mixtures contain more than one pure substance.
- Mixtures can be homogeneous (uniform composition) or heterogeneous (non-uniform composition).
2.1 What is a Mixture?
- Mixtures are composed of more than one pure substance.
- Mixtures can be separated by physical processes, like evaporation.
- Examples of mixtures include seawater, soil, and air.
2.1.1 Types of Mixtures
- Homogeneous mixtures (solutions) have uniform composition throughout.
- Heterogeneous mixtures have non-uniform composition.
- Examples of homogeneous mixtures are salt dissolved in water and sugar dissolved in water.
Activity
- The activity involves creating different mixtures (e.g., copper sulfate in water) and observing uniformity.
- Homogeneous mixtures are uniform in colour and texture.
- Heterogeneous mixtures are non-uniform in colour and texture.
2.2 What is a Solution?
- A solution is a homogeneous mixture of two or more substances.
- Solutions can be solids, liquids, or gases.
- The component present in larger quantity is the solvent.
- The component dissolved is the solute.
- Examples of solutions include sugar in water and air.
2.2.1 Concentration of a Solution
- Dilute solutions have a small amount of solute.
- Concentrated solutions have a large amount of solute.
- Saturated solution is the maximum amount of solute that can dissolve at a given temperature.
- Solubility is the amount of solute that can dissolve in a given amount of solvent at a specific temperature.
2.2.2 What is a Suspension?
- Suspensions are heterogeneous mixtures where solid particles are dispersed in a liquid.
- Particles in a suspension are visible and will settle out over time.
- Suspension is easily separated by filtration.
2.2.3 What is a Colloidal Solution?
- Colloids are heterogeneous mixtures.
- Colloid particles are too small to see individually.
- Colloids display the Tyndall effect (scattering of light).
- Colloids are stable; particles do not settle out.
2.3 Physical and Chemical Changes
- Physical changes do not alter composition (e.g., melting, dissolving).
- Chemical changes alter composition (e.g., burning, rusting).
2.4 What are the Types of Pure Substances?
- Pure substances are classified as elements or compounds based on their composition.
2.4.1 Elements
- Elements are basic forms of matter.
- Elements cannot be broken down into simpler substances by chemical reactions.
- Examples include gold, iron, and oxygen
2.4.2 Compounds
- Compounds are substances formed by the chemical combination of two or more elements.
- Compounds have different properties compared to the elements from which they are made
- Examples include water (H₂O) and salt (NaCl)
2.2 Mixtures and Compounds
- Mixtures are physically combined substances with variable compositions and properties.
- Compounds are chemically combined substances with fixed compositions and properties different from their component elements
Exercises
- Included exercises for separation techniques, identifying solutions, classifying mixtures.
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Description
Explore the concepts of pure substances and mixtures in this quiz based on Chapter 2. You'll learn about the properties of matter, the distinctions between homogeneous and heterogeneous mixtures, and how mixtures can be separated. Test your understanding of these fundamental concepts in chemistry!