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Unit B Matter and Chemical Change Section 1.0 Physical and Chemical Properties • Chemistry is the science of studying the properties of matter and how it changes. •/What-Is-the-Importance-of-Chemistry http://www.youtube.com/watch?v=nsbXp64YPRQ • Matter is anything that has mass and occupies space. Section 1.1 Laboratory Safety Household Hazardous Materials Warning Labels: Some materials used in the lab and at home are hazardous and therefore have a hazard symbol. These symbols show the reader two things: 1. Shape = how hazardous the material is Triangle means “caution” Diamond means “warning” Octagon means “danger” 2. Picture = the type of hazard *See fig. 1.2 (p. 94) for all hazard symbols WHMIS Symbols: The Workplace Hazardous Materials Information System is another system of warning symbols designed to protect people who use harmful substances at work. WHMIS game Mr Bean Chemistry Lab Read Lab Safety Rules (p 95) Read Toolbox 1 (p 478) Do Worksheet “Safety in the Science Classroom” Section 1.2 Organizing Matter Matter exists in different states (solids, liquids and gases). The state of matter depends on its temperature: Low Temperature High Temperature Properties - characteristics used to describe a substance Physical Properties – these properties explain the appearance and composition of a substance. Examples include: Texture -Density Shape - Melting Point - Boiling Point Size Colour - Solubility - Ductility Odour - Malleability Mass Physical Change – Any change not involving a change in the substance's chemical identity. A physical change involves only a change in physical properties. In other words, the type of matter has not been changed. Examples include: Changes of state Dissolving Absorption of water into a towel Crumpling a piece of paper Pulling copper into a thin wire (change of shape, but not change of composition) Cutting a material Breaking glass Writing on a Sheet of Paper Chemical Properties – these properties explain how a substance reacts with another substance. Examples include pH Reactivity Toxicity Combustibility Chemical stability Behavior in air Chemical Change – when two or more substances react and one or more new substances are formed having different properties from the initial substances. Examples include: Combustion Mixing an acid and a base Photosynthesis Iron Rusting Do Investigation B-1 P.100 Identifying the Mystery Substance Pure Substances and Mixtures A pure substance consists of only one kind of matter and has its own unique set of properties. Elements and compounds are pure substances. Elements: a material that cannot be further broken down. These are the basic building blocks for compounds. Compounds: two or more elements chemically combined in a specific arrangement and proportion. A mixture is a physical combination of pure substances. Each substance retains its properties since there is no chemical reaction that takes place. http://www.bbc.co.uk/bitesize/ks3/sci ence/chemical_material_behaviour/ compounds_mixtures/activity/ There are 4 types of mixtures: 1.Mechanical mixture – each substance that makes up the mixture is distinct or visible. An example is chili. 2. Solution – the substances are NOT visibly distinct from each other. One substance, the solute, is dissolved into the other, the solvent. An example is Kool-Aid. Substances dissolved into water are called aqueous solutions. 3.Suspension – tiny particles of one substance are held within another in a cloudy mixture. These particles can be filtered out. An example is tomato juice. 4.Colloid - another cloudy suspension, but with particles so tiny that they cannot be filtered out. An example is milk. Complete the figure in your notes by looking at the Figure 1.11 on page 103 Now Do Check and Reflect P.104 #1-9 Section 1.3 Observing Changes in Matter Recall from section 1.2 that in a physical change only the substance’s physical properties change. For example, a change in state. No new substances are produced. A chemical change is when two or more substances react and create new materials which have different properties from the initial substances. Evidence of chemical change is as follows . . . 1. Change in color 2. Change in odor 3. Formation of a solid or a gas (precipitate) 4. Release or absorption of heat or light energy ( warm or cold) Sometimes, it is impossible to tell if a substance has undergone a physical or a chemical change without chemical analysis in a lab. Do Investigation B-2 P. 106 Investigating Physical and Chemical Change Controlling Changes in Matter Understanding and controlling changes in matter can help us meet our basic needs. One example is freeze-drying. Food is frozen, then put under pressure so that the ice sublimes, and about 98% of water is removed. Food that has undergone this process is about 10% of its initial mass and can be eaten months, sometimes years later. The technique can be used by biologists to study tissue samples or restore important water-damaged documents. Another example is MRE or “Meal Ready to Eat”. The US Army uses special packaging to heat their freeze-dried foods called a “Flameless Ration Heater”. This package contains magnesium, iron and salt – when water is added, heat is released and it warms the MRE so it is ready to eat! Scientists are also able to change common materials into other substances. Corn is first fermented, then new substances are collected, purified and made into biodegradable plastics (pop bottles), solvents such as nail polish remover and gasohol which can be used as vehicle fuel. Now Do Check and Reflect P.109 # 1-7 And Section Review Quiz next class!!