Real-world examples can help students with these concepts. For example, sugar is sweet, water is wet, and a sugar solution is sweet and wet. Demonstrate making solutions by dissolving sugar in water, and the reverse by gently heating small volumes of the solution in evaporating dishes.
Demonstrate other types of mixtures, such as suspensions, gels and foams, with flour in water, jelly and whipped cream. Students will encounter many examples of mixtures throughout their chemistry studies, providing them regular opportunities to reinforce their understanding of mixtures and solutions. Need some inspiration for planning a lesson? Download this example lesson plan that incorporates these ideas MS Word or pdf.
Download this example lesson plan that incorporates these ideas rsc. It is helpful to emphasise that learning science is as much about learning a new language as it is about learning concepts and skills.
When solutions form, many students think the mass of the solute is lost as it disappears into solution, although they will readily describe sugary water as tasting sweet. They may rarely recognise that the properties of a mixture are dependent on its exact composition. Finally, students rarely recognise water a very common solvent as being particulate. Student-drawn representations of sugar dissolving in water often shows sugar particles in a continuous background of water. Chemical misconceptions contains many useful ideas and worksheets to help diagnose students thinking.
You have a beaker of water that weighs g. You add 10 g copper sulfate to the beaker of water. Initially, the copper sulfate solid can be seen in the water, but 10 minutes later the solid cannot be seen and the water turns blue. What is the mass of the beaker and its contents when the copper sulfate is first added? What is the mass when it has all finally dissolved in the water? Explain your answers. Students will not gain a proficient understanding of mixtures and solutions the first time they encounter these ideas.
Regular formative assessment will help them to develop their understanding. For example, ask students to:. The nature of chemical substances is a fundamental concept in chemistry, underpinning most of 14—16 chemistry. Concepts of elements, compounds, atoms and molecules will add to the understanding of mixtures and solutions, alongside separation techniques.
These concepts will be reinforced and contextualised at 14—16, when students study materials such as crude oil and rock ores. Students will also need to understand the nature of chemical models. Lithium-ion batteries will power the next generation of electric cars, but how can we mine lithium with minimal impact on the environment?
Identify each substance as a compound, an element, a heterogeneous mixture, or a homogeneous mixture solution. A pure substance is a form of matter that has a constant composition and properties that are constant throughout the sample. Mixtures can be classified as homogeneous or heterogeneous.
Compounds are substances that are made up of more than one type of atom. Elements are the simplest substances made up of only one type of atom. This page was constructed from content via the following contributor s and edited topically or extensively by the LibreTexts development team to meet platform style, presentation, and quality:.
Chem1 Virtual Textbook. Learning Objectives Explain the difference between a pure substance and a mixture. Explain the difference between an element and a compound. Explain the difference between a homogeneous mixture and a heterogeneous mixture.
Phase A phase is any part of a sample that has a uniform composition and properties. If it is pure, the substance is either an element or a compound. If a substance can be separated into its elements, it is a compound. If a substance is not chemically pure, it is either a heterogeneous mixture or a homogeneous mixture. If its composition is uniform throughout, it is a homogeneous mixture. Solution A Tea is a solution of compounds in water, so it is not chemically pure.
It is usually separated from tea leaves by filtration. B Because the composition of the solution is uniform throughout, it is a homogeneous mixture. A Orange juice contains particles of solid pulp as well as liquid; it is not chemically pure. B Because its composition is not uniform throughout, orange juice is a heterogeneous mixture.
A A compact disc is a solid material that contains more than one element, with regions of different compositions visible along its edge. Hence, a compact disc is not chemically pure. The word 'pure' is used in chemistry in a different way from its everyday meaning.
For example, shops sell cartons labelled as 'pure' orange juice. The label means that the contents are just orange juice, with no other substances added. However, the juice is not pure in the chemical sense because it contains different substances mixed together. In chemistry:.
Hydrogen and oxygen are both gases. Together, as a mixture, hydrogen and oxygen can react and form water. Water is a compound of hydrogen and oxygen. There are important differences between the properties of a mixture and a compound. In this table, the column 'Mixture' refers to the gasses hydrogen and oxygen, and the column named 'Compound' refers to water.
Pure substances have a sharp melting point but mixtures melt over a range of temperatures.
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