Matter in Your World在你的世界的事情.doc

Matter in Your World4.1 NotesMatter is any material that occupies space and has mass. Matter includes all solids, liquids and gases. These forms of matter have different characteristics.The characteristics that are used to describe matter are called properties. Every material has its own set of properties. Under normal conditions, water freezes at 0oC and boils at 100oC, it is also clear, colourless, odourless liquid. Whenever you see a material that has more than one set of properties, you know that it is a mixture. A mixture contains more than one kind of matter A mixture contains more than one kind of matter combined in such a way that each keeps its own properties. Mixtures that are made up of parts that can be seen are called heterogeneous. Heterogeneous means made up of parts, or mixed.Materials that have only one set of properties are called homogeneous. Homogeneous means that every part of the material is the same. An example of heterogeneous material is on page 103 in the textbook. (Cement or concrete is heterogeneous.Check Your Understanding 4.11. Some properties of water are clear, colourless, ordourless, freezes at 0oC, boils at 100oC, dissolves many substances. Some properties for glass are transparent, hard, durable, breaks easily, inflexible Some properties for steel are opaque, heavy, strong, will rust and corrode, inflexible.2. You cannot distinguish between the different components in a homogeneous mixture, so the mixture appears the same all over. A hetergeneous mixture does not appear the same all over, and the different components are visible.3. (answers will vary)4. a) The water in one river will have one set of properties. b) River water is heterogeneous. The brown colour is river water indicates the presence of dirt particles.5. (students answers will vary but they should realize that most materials are heterogeneous)4.2 Notes What is a mixture? Anything with two distinct sets of properties must be a mixture of at least two materials. When a mixtures different parts can be identified this easily, the mixture is usually called a mechanical mixture. Homogeneous mixtures is called a solution. Solutions are everywhere. Two thirds of Earth is covered with a liquid solution - the salty water of the oceans. Earth is surrounded by a gas slution that we call air - a homogeneous mixture of oxygen, nitrogen, and other gases. There are even solid solutions.Mixtures are absolutely everywhere you look. Mixtures are the form for most things in nature. Rocks, air, or the ocean, they are just about anything you find. They are substances held together by physical forces, not chemical. That statement means the individual molecules enjoy being near each other, but their fundamental chemical structure does not change when they enter the mixture. When you see distilled water, its a pure substance. That fact means that there are just water molecules in the liquid. A mixture would be a glass of water with other things dissolved inside, maybe salt. Each of the substances in that glass of water keeps the original chemical properties. So, if you have some dissolved substances, you can boil off the water and still have those dissolved substances left over. Because it takes very high temperatures to boil salt, the salt is left in the container. Check Your Understanding 4.21. You need two properties to observe a heterogeneous mixture.2. A) A solution is a homogeneous mixture. A solute is dissolved in a solvent. B) For a mixture to be a solution, the combination of materials needs to be the same throughout. The different bits of the materials cannot be seen. 3. Pour some of the liquid into a cup to a depth of about 1 cm. Leave the cup uncovered. After a few days, check the cup. The liquid should have evaporated. If crystals are present then the liquid was probably a mixture of salt and water. Otherwise, it was most likely pure water.4. a) Ocean water has all the properties of water, in addition to the properties of salt. The individual bits of water are exactly the same throughout the mixture.4. b) Ocean water has all the properties of salt, in addition to the properties of water. The bits of salt are the same throughout the mixture, but they are not visible.5. a) If the bits and blobs were not part of the mixture, but came from somewhere else, then the mixture could be homogeneous. b) You would need evidence that the bits and blobs are part of the mixture. If they were part of the mixture, then the mixture would be heterogeneous, and your partner would be correct.6. A cloud is homogeneous since the water droplets are evenly mixed throughout, and different kinds of particles are not visible.7. The foam on top of the waves is the result of bubbles of air being mixed with the water as the waves break along the shoreline.Check Your Understanding 4.31. All matter is made up of tiny particles. Each pure substance has its own kind of particle.2. Pure substances have one kind of particle. Mixtures have at least two kinds of particles.3. If the particles are extremely small, it may be difficult to tell the difference between a pure substance and a mixture.4. a) Students diagrams should indicate the presence of both alcohol and iodine particles; however, with the iodine particles evenly distributed among the alcohol particles.b) The particles of iodine have one set of properties, and they are all the same. The particles of alcohol have a different set of properties. When the two are mixed, the resulting solution has both sets of properties. 4. c) The properties became blended because the iodine particles are evenly scattered among the alcohol particles.Chapter 4 Review2. a) Both mixtures and solutions have more than one type of matter.b) A solution is homogeneous because the particles are evenly mixed, and it has the same set of properties throughout.c) A pure substance must be homogeneous.d) If a mixture has more than one set of properties, it is heterogeneous.e) Properties help to distinguish different particles in a mechanical mixture.f) Pure substances have only one kind of particle.3. a) Examples of materials that are definitely heterogeneous are concrete, an oil spill in water, mineral rocks, Italian salad dressing, and a sand-and-water mixture.3 b) Examples of materials that are definitely homogeneous are coffee, apple juice, vinegar, a metal alloy, and a mixture of alcohol and water.c) Milk appears homogeneous but it is, in fact, heterogeneous.4. A mixture is a material that has more than one kind of matter and therefore more than one set of properties. Examples are orange juice, hand cream, and buttermilk. A pure substance is a material that is made up of only one kind of particle, with the same properties throughout. Examples are gold, alcohol, distilled water, and oxygen.5. A theory that explains the make-up of matter is the particle theory of matter. The two main ideas of this theory are these: 1) All matter is made up of tiny particles.2) Each pure substance has its own kind of particle, different from the particles of other pure substances.6 a) Diagram C represents a homogeneous mixture. b) Diagram A represents a mechanical mixture. c) Diagram B represents a pure substance. d) Diagram D represents a different pure substance.8. a) The model should show regularly spaced styro-peanuts of one colour for each pure substance.b) The model should show a combination of two colours of peanuts, with an uneven distribution for Heterogeneous.c)The model should show a combination of two colours of peanuts, evenly distributed throughout for Homogeneous.9. a) In order to separate a solution allow the mixture, to stand for a period of time to allow the oil and water to separate into layers.b) Separate the two materials according to colour, lustre, or shape. You could also use a magnet to separate the paper clips.c) Add water to the mixture and stir. The sugar will dissolve, and the sawdust will float to the surface. Use a screen or a sieve to remove the sawdust. Allow the water to evaporate to leave the sugar behind, at the bottom of the container.11. a) A soft drink is a homogenous mixture, since the particles appear to be the same throughout and are evenly mixed.b) When the soft drink is poured into a glass, it is heterogeneous. There is evidence of at least two different kinds of matter. Particles (bubbles) can be seen, and they are unevenly distributed in the mixture.12. The particles in a crystal of sugar and in a sugar cube are the same. Since they both have the same particles, they have the same properties, as well.13. If the mixture is uneven, it is heterogeneous. If the material is the same throughout, and the particles are evenly mixed, it is homogeneous. Potting soil and pesticide pellets are heterogeneous. Fertilizer is homogeneous.14. An examination of potting soil easily reveals the mixtures different materials with varying sizes and shapes. The hand lens would be needed, however, for b and c