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Physical versus Chemical Properties

Physical versus Chemical Properties. Chapter 2 Section 2 Describing matter. Reviewing MATTER. Matter: anything that has mass and takes up space Mass – the amount of matter in something Volume – the amount of space something occupies Which of the following is matter? A car? A box? You?.

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Physical versus Chemical Properties

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  1. Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

  2. Reviewing MATTER • Matter: anything that has mass and takes up space • Mass – the amount of matter in something • Volume – the amount of space something occupies • Which of the following is matter? • A car? • A box? • You?

  3. What is a property? • Property: a characteristic of a substance that can be observed

  4. Physical Property Physical property: a property that can be observed without changing the identity of the substance. • Examples: • luster • malleability: the ability to be hammered into a thin sheet • ductility: the ability to be stretched into a wire • melting point • boiling point • density • solubility • specific heat

  5. Physical Properties • Color • Shape • Size • Density • Melting Point • Boiling Point

  6. Example of Physical Property • The physical properties of sodium metal can be observed or measured. It is a soft, lustrous, silver-colored metal with a relatively low melting point and low density. • Hardness, color, melting point and density are all physical properties.

  7. Special Physical Properties • Melting point: the temperature at which a substance changes from a solid to a liquid at a given pressure water = 0oC • Boiling point: the temperature at which a substance changes from a liquid to a gas at a given pressure water = 100oC

  8. Thermal Density Solubility State Ductility Malleability

  9. Chemical Properties • Chemical property: a property that can only be observed by changing the identity of the substance

  10. Chemical Properties Examples of Chemical Properties • Reactivity with oxygen • Nonreactivity with oxygen • Flammability • Nonflammability

  11. Chemical Properties

  12. Comparison of Physical and Chemical Properties

  13. Density • Density is the amount of mass per unit of volume. • Density can be used to identify a substance. • The density of water is 1.0g/mL

  14. Density Calculations • Calculations: D = m/V • Ex: A cube has a mass of 2.8 g and occupies a volume of 3.67 ml. Would this object float or sink in water? Mass = 2.8 g Volume = 3.67 mL D = 2.8g/3.67 mL= 0.76 g/mL • This object would float in water because its density is less than water (1.0 g/mL).

  15. More Density Calculations • Ex: A liquid has a mass of 25.6 g and a volume of 31.6 mL. Use the table below to identify the substance. M=25.6 g V=31.6 mL D = 25.6 g/31.6 mL D= 0.81 g/mL The substance is ethanol.

  16. Physical Change Physical change is the change that affects one or more physical properties of a substance. • Imagine breaking a piece of chalk into two pieces. What are you changing? What is not being changed? • Physical changes do not change the identity of the matter involved

  17. Physical Change • Freezing water for ice cubes • Sanding a piece of wood • Cutting your hair • Crushing an aluminum can • Bending a paper clip • Mixing oil and vinegar

  18. Chemical Change Chemical change happens when two or more substance are changed into one or more new substances with different properties. • Properties of a substance describe which chemical changes will or will not happen • Chemical change and properties are not the same, a change is the process in which it changes

  19. Chemical Change Examples of Chemical Changes • Soured milk • Effervescent tablets • Statue of Liberty • Baking a cake

  20. Chemical Change Clues that chemical change has occurred • Changes in color • Heat • Fizzing and foaming • Production of sound or light

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