Elements, Compounds And Mixtures
Overview
Everything around you - the air you breathe, the water you drink, the screen you are reading - is made from just over a hundred different elements. Sometimes those elements exist on their own, sometimes they are chemically bonded into compounds, and sometimes they are simply mixed together without reacting.
In this lesson you will learn to classify substances as elements, compounds, or mixtures, understand how purity is defined in chemistry, and master the separation techniques that chemists use to pull mixtures apart.
Objectives
- Understand how to classify a substance as an element, compound or mixture
- Understand that a pure substance has a fixed melting and boiling point, but that a mixture may melt or boil over a range of temperatures
- Describe experimental techniques for the separation of mixtures: simple distillation, fractional distillation, filtration, crystallisation and paper chromatography
- Understand how a chromatogram provides information about the composition of a mixture
- Understand how to use the calculation of Rf values to identify the components of a mixture
- Investigate paper chromatography using inks/food colourings
Lesson Note
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Lesson Evaluation
Congratulations on completing the lesson on Elements, Compounds And Mixtures. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- Which of the following is a compound? A) Oxygen gas (O2) B) Iron filings C) Carbon dioxide (CO2) D) Air Answer: C
- A pure substance can be identified because it: A) Dissolves in water B) Has a fixed melting point C) Is always a solid D) Melts over a range of temperatures Answer: B
- Which technique separates an insoluble solid from a liquid? A) Distillation B) Chromatography C) Filtration D) Crystallisation Answer: C
- In chromatography, the Rf value is calculated by dividing: A) Distance moved by solvent by distance moved by substance B) Distance moved by substance by distance moved by solvent front C) Mass of substance by mass of solvent D) Time taken by substance by time taken by solvent Answer: B
- Fractional distillation is used to separate: A) An insoluble solid from a liquid B) A dissolved solid from a solution C) Miscible liquids with different boiling points D) Immiscible liquids Answer: C
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Available on the Green Bridge App
Download the Green Bridge CBT app on your phone or computer to access full lesson notes, practice questions, and more.
Practice Mock Questions
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