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Topic 2. Unit 2 – Matter and Chemical Change. There are different ways that matter can change. Examples? evaporate change temperature burn up dissolved rust break apart change color explodes We can classify theses changes as physical or chemical .
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Topic 2 Unit 2 – Matter and Chemical Change
There are different ways that matter can change. • Examples? • evaporate • change temperature • burn up • dissolved • rust • break apart • change color • explodes • We can classify theses changes as physical or chemical Topic 2 – Changes in Matter
A substance changes form but not what it’s made of (composition) • Some form of energy is usually involved but you haven’t changed the actual chemicals you started with. • Examples: • Ice melting • H2O solid to H2O liquid Physical Changes
Physical Changes - changes in the properties of matter that do not effect its composition • Examples: • Heating water • raises its temperature, but it is still water • Evaporating butane from a lighter • Dissolving sugar in water • even though the sugar seems to disappear, it can easily be separated back into sugar and water by evaporation Physical Changes
Boiling = liquid to gas • Melting = solid to liquid • Subliming = solid to gas • Condensing = gas to liquid • Freezing = liquid to solid • state changes require heating or cooling the substance Phase Changes are Physical Changes
One or more new substances are produced Chemical Changes
Colour Change • Odor Change • State Change – forming a precipitate (solid) or bubbles (gas) • Energy change • Heat or light given off or absorbed • Difficult to reverse Evidences for Chemical Change
These are traits or characteristics that matter possesses. • Properties can be physical or chemical. • Physical Properties • they can be observed or measured • they do not involve forming a new substance • Examples: • Density, colour, state, solubility conductivity, melting point Properties
These are ways that one substance reacts with another substance • Examples: • combustible, reacts in water, toxic explosive, corrosive Chemical Properties
Physical Properities can be further classified into Quantitative and Qualitative Properties Quantitative properties have numbers and units. Eg. Height 300 cm Qualitative properties describes a substance without units or numbers. Eg. Colour - blue Quantitative vs. Qualitative