physical versus chemical properties chapter 2 section 2 describing matter

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Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

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Page 1: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

Physical versus Chemical Properties

Chapter 2 Section 2Describing matter

Page 2: Physical versus Chemical Properties Chapter 2 Section 2 Describing 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?

Reviewing MATTER

Page 3: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

What is a property?

• Property: a characteristic of a substance that can be observed

Page 4: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

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

Page 5: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

Physical Properties

• Color• Shape • Size • Density• Melting Point• Boiling Point

Page 6: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

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.

Page 7: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

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

Page 8: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

• Thermal

• Density

• Solubility

• State

• Ductility

• Malleability

Page 9: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

Chemical Properties

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

Page 10: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

Chemical Properties

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

Page 13: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

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

Page 14: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

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 mLD = 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).

Page 15: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

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.

Substance Density (g/ mL)

Mercury 13.6

Water 1.00

Ethanol 0.81

M=25.6 g V=31.6 mL

D = 25.6 g/31.6 mL

D= 0.81 g/mL

The substance is ethanol.

Page 16: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

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

Page 17: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

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

Page 18: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

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

Page 19: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

Chemical Change

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

Page 20: Physical versus Chemical Properties Chapter 2 Section 2 Describing matter

Chemical Change

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