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10.4.10 physical changes. Getting started…. Bell Ringer : Why do the reactants and the products of a chemical equation have to balance? Law of conservation of matter; matter is not created or destroyed but only changes forms.
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Getting started… • Bell Ringer : Why do the reactants and the products of a chemical equation have to balance? • Law of conservation of matter; matter is not created or destroyed but only changes forms • Engagement: What changes can you make to your appearance that are not permanent? (below your bell ringer)Describe 3 of them.
Agenda 10.4.10 • Discuss and describe physical changes (including changes in size, shape, and state) • Bell Ringer : why do the reactants and the products of a chemical equation have to balance? • Engagement: what changes can you make to your appearance that are not permanent? Describe 3 of them. • Modeling: Can we undo it? • Guided Practice: some examples of physical changes • Independent Practice: Now you do it • Closure: Which of the physical changes are you most like to use? Why? How?
Stdsindicators: this week we will • Compare physical changes (including changes in size, shape, and state) to chemical changes that are the result of chemical reactions (including changes in color or temperature and formation of a precipitate or gas). • Because physical and chemical changes affect substances in different ways. Physical changes do not change the composition of a substance, only the physical properties. Chemical changes result in the formation of one or more new substances with new chemical and physical properties.
Physical changes: what are they? • physical changes (including changes in size, shape, and state) • What is state? • Physical changes do not change the composition of a substance, only the physical properties. • What is composition?
Evidences of a Physical Change: • Change in State of Matter • When a substance changes from one state of matter to another (for example, changing from solid to liquid, from liquid to solid, or from liquid to gas), the composition of the substance remains the same. • Examples of change in state might include: melting of ice cream, hardening of melted wax, or evaporation of water from wet clothes. • When a substance changes directly from a gas to a solid (the forming of frost from water vapor) or from a solid to a gas (dry ice, solid air fresheners) that change of state is called sublimation.
Change in Size or Shape • When a substance changes in size or shape (for example, cutting, tearing, dissolving, stretching, or wrinkling), its composition remains the same. • Examples of change in size or shape might include: shredding paper, • dissolving sugar in water, • stretching a rubber band, • wadding up a piece of paper, • or denting a piece of metal.
Change in Size or Shape When a substance changes in size or shape (for example, cutting, tearing, dissolving, stretching, or wrinkling), its composition remains the same.
Changes in States of Matter • Essential – Demonstrate a solid changing to a liquid by observing ice melt in a clear container or placing chocolate candy under a heat source. Quadrant A • Essential – Demonstrate a liquid changing into a solid by placing liquid water in a freezer. Students will observe the change the following day. Students pour melted chocolate onto wax paper and allow it to cool so that it changes into a solid form. Quadrant A • Essential – Demonstrate a liquid changing to a gas by placing a salt water solution in a pan to be observed over a period of 2-3 days. Quadrant A • Essential – Demonstrate a solid changing to a gas by bringing in dry ice or by comparing a new solid air freshener to a used solid air freshener. Quadrant A • Essential -Students identify, describe characteristics, and list examples of each phase of matter on a student created chart. Quadrant A • Essential -Students draw examples of each state of matter and explain the distinguishing properties of each. Students also draw the arrangement of the atoms in each. Quadrant B • Changes in Size or Shape • Essential – Demonstrate changes in size or shape by: • shredding, tearing, or cutting paper • dissolving sugar or salt in water • stretching a rubber band or silly putty • wadding up a piece of paper • denting a piece of metal such as a soda can