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Matter. Physical and Chemical Changes. Everything that has mass and volume is called matter. What is matter?. What kind of changes does matter undergo?. All matter, regardless of state, undergoes physical and chemical changes. These changes can be microscopic or macroscopic.

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physical and chemical changes

Matter

Physical and Chemical Changes

slide3

What kind of changes does matter undergo?

All matter, regardless of state, undergoes physical and chemical changes. These changes can be microscopic or macroscopic.

slide5

What is a physical change?

A physical change occurs when the substance changes state but does not change its chemical composition. For example: water freezing into ice, cutting a piece of wood into smaller pieces, etc. The form or appearance has changed, but the properties of that substance are the same (i.e. it has the same melting point, boiling point, chemical composition, etc.)

slide6

Characteristics of Physical Changes

  • Density
  • Electrical conductivity
  • Solubility
  • Adsorption to a surface
  • Hardness
  • Melting point
  • Boiling point
  • Vapor pressure
  • Color
  • State of matter
slide7

Physical and chemical properties may be intensive or extensive.

Intensive and Extensive Properties

slide8

Intensive properties such as density, color, and boiling point do not depend on the size of the sample of matter and can be used to identify substances.

What are intensive properties?

slide9

Extensive properties such as mass and volume do depend on the quantity of the sample.

What are extensive properties?

slide10

Physical properties are those that we can determine without changing the identity of the substance we are studying.

How can we identify physical properties?

slide11

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.

Examples of physical properties:

slide13

States of Matter

(And how the Kinetic Molecular Theory affects each)

  • Solids
  • Liquids
  • Gases
  • Plasma
slide15

Solids

  • Have a definite shape
  • Have a definite volume

Kinetic Molecular Theory

Molecules are held close together and there is very little movement between them.

slide16

Liquids

  • Have an indefinite shape
  • Have a definite volume

Kinetic Molecular Theory:

Atoms and molecules have more space between them than a solid does, but less than a gas (ie. It is more “fluid”.)

slide17

Gases

  • Have an indefinite shape
  • Have an indefinite volume

Kinetic Molecular Theory:

Molecules are moving in random patterns with varying amounts of distance between the particles.

slide18

Kinetic Molecular Model of Water

At 100°C, water becomes water vapor, a gas. Molecules can move randomly over large distances.

Between 0°C and 100 °C, water is a liquid. In the liquid state, water molecules are close together, but can move about freely.

Below 0°C, water solidifies to become ice. In the solid state, water molecules are held together in a rigid structure.

slide20

On earth we live upon an island of "ordinary" matter. The different states of matter generally found on earth are solid, liquid, and gas. We have learned to work, play, and rest using these familiar states of matter. Sir William Crookes, an English physicist, identified a fourth state of matter, now called plasma, in 1879.

slide21

Plasma

Plasma is by far the most common form of matter. Plasma in the stars and in the tenuous space between them makes up over 99% of the visible universe and perhaps most of that which is not visible.

slide22

EXAMPLES:

  • Computer chips and integrated circuits
  • Computer hard drives
  • Electronics
  • Machine tools
  • Medical implants and prosthetics
  • Audio and video tapes
  • Aircraft and automobile engine parts
  • Printing on plastic food containers
  • Energy-efficient window coatings
  • High-efficiency window coatings
  • Safe drinking water
  • Voice and data communications components
  • Anti-scratch and anti-glare coatings on eyeglasses and other optics
density

Density = mass (g) D = g or g volume (ml) ml cm3

  • Note ml = cm3

m

Density

v

D

learning check d1

Osmium is a very dense metal. What is its

density in g/cm3 if 50.00 g of the metal occupies

a volume of 2.22cm3?

1) 2.25 g/cm3

2) 22.5 g/cm3

3) 111 g/cm3

Learning Check D1

lecturePLUS Timberlake

solution

2) Placing the mass and volume of the osmium metal into the density setup, we obtain

D = mass = 50.00 g =

volume 2.22 cm3

= 22.522522 g/cm3 = 22.5 g/cm3

Solution

lecturePLUS Timberlake

volume displacement

A solid displaces a matching volume of water when the solid is placed in water.

33 mL

25 mL

Volume Displacement

lecturePLUS Timberlake

learning check

What is the density (g/cm3) of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL?

1) 0.2 g/ cm3 2) 6 g/m3 3) 252 g/cm3

33 mL

25 mL

Learning Check

lecturePLUS Timberlake

solution1

2) 6 g/cm3

Volume (mL) of water displaced

= 33 mL - 25 mL = 8 mL

Volume of metal (cm3)

= 8 mL x 1 cm3 = 8 cm3

1 mL

Density of metal =

mass = 48 g = 6 g/cm3

volume 8 cm3

Solution

lecturePLUS Timberlake

learning check3

Which diagram represents the liquid layers in the cylinder?

(K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL)

1) 2) 3)

K

W

V

Learning Check3

V

K

W

W

V

K

lecturePLUS Timberlake

solution2

(K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL)

1)

V

Solution

W

K

lecturePLUS Timberlake

slide31

What are chemical changes?

A chemical change occurs when a substance changes into something new. This occurs due to heating, chemical reaction, etc. You can tell a chemical change has occurred if the density, melting point or freezing point of the original substance changes. Many common signs of a chemical change can be seen (change in color, change in temperature, formation of a gas, emission of light, formation of a precipitate).

slide32

Characteristics of Chemical Changes

  • Ability to act as reducing agent
  • Reaction with other elements
  • Decomposition into simpler substances
  • Corrosion
  • Reaction with acids
  • Reaction with bases (alkalis)
  • Reaction with oxygen (combustion)
  • Ability to act as oxidizing agent
slide33

Chemical properties describe the way a substance can change or react to form other substances. These properties, then, must be determined using a process that changes the identity of the substance of interest.

What are chemical properties?

slide34

One of the chemical properties of alkali metals such as sodium and potassium is that they react with water. To determine this, we would have to combine an alkali metal with water and observe what happens.

  • In other words, we have to define chemical properties of a substance by the chemical changes it undergoes.

How can chemical properties be identified?

evidence of chemical change

Bubbles of gas appear

  • A precipitate forms
  • A color change occurs
  • The temperature changes
  • Light is emitted
Evidence of Chemical Change
slide36

Comparison of Physical and Chemical Properties

Create a Venn diagram to compare and contrast physical and chemical properties