Testing

1
The Key to the Universe
2
Pure Substances

• Pure Substances either all one element or all
  one compound. Have definite unchanging
  properties
• Types
• a) Elements Au, O2
• b) Compounds pure water

3
The Key to the Universe
Mixtures
4
Homogeneous Mixtures

• Homogeneous mixture uniform mixture of two or
  more elements and compounds (only one phase)
• Types
• a) Solutions liquid homogeneous mixtures
• Examples
• Kool-Aid
• Salt Water

5
Homogeneous Mixtures

• b) Alloys Solid uniform mixtures. Usually
  metals.
• Stainless Steel Iron and Cr
• Gold Ring Au, Cu Zn

6
Heterogeneous Mixtures

• Definition nonuniform mixture, composed of two
  or more phases
• Phase One physical state with definite
  boundaries
• Examples
• Ice Water Two Phases (water ice)
• Italian dressing More than two phases
• Granite Multiple phases
• Zinc and Sulfur

7
(No Transcript)
8
Physical Properties

• Physical properties can be observed without
  changing the substance into another substance
• Examples
• Melting Point/Freezing Point
• Boiling Point
• Hardness
• Solubility
• Malleability
• Ductility

9
Physical Properties
10
(No Transcript)
11
(No Transcript)
12
Can an elephant swim?
13
Physical Properties Density

• History Archimedes story
• Density mass per unit volume
• D m/V
• Mass ? Grams
• V ? mL or (cm3)
• D ? g/mL

14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
Physical Properties Density

• Intensive property
• Volume formulas
• Rectangular
• Cylinder

18
Physical Properties Density

• 6. Solving for variables
• a. Algebra
• 3 x/8 2 6/x
• b. Density
• Solve for m
• Solve for V

19
Physical Properties Density

• A ring has a mass of 8.99 g and a volume of 0.796
  mL. Is the ring gold (19.3 g/mL)? (Ans 11.3
  g/mL)
• A substance masses 47.5 g. It is put into a grad
  cylinder containing 12.5 mL of water. After
  immersing the substance, the total volume is 31.8
  mL. What is the density? (Ans 2.46 g/mL)

20
Physical Properties Density

• Salt has a density of 2.16 g/mL. What is the
  volume of 485 g of salt? (Ans 225 mL)
• What is the mass of 1.52 L of kerosene (r 0.82
  g/mL)? (Ans 1200 g)
• What volume would 0.450 kg of lead occupy (r
  11.3 g/cm3) (Ans 39.8 cm3)
• A cylinder has a radius of 2.00 cm and a height
  of 10.0 cm. If the cylinder is filled with 0.289
  grams of a gas, density? (Ans 0.00230 g/cm3)

21
(No Transcript)
22
Chemical Properties

• Chemical Change one substance is changed into
  another substance
• Chemical Properties tendency of a substance to
  react with other substances
• Examples
• Flammability
• Will it rust (oxidize)?
• Acid or base?

23
Chemical Properties

• Atoms rearrange and bonds are made and broken
• 2H2 O2 ? 2H2 O

24
Chemical Properties

• Recognizing a chemical change
• Properties change (rust is different than iron)
• Gets hotter or colder
• Exothermic Gives off heat (burning gas,
  exercise)
• Endothermic Absorbs heat (cooking)
• Color change
• Gas given off
• Light produced (glow stick)

25
Law of Conservation of Mass

• Antoine Lavosier (1789)
• Law of cons. of mass mass is neither created
  nor destroyed in an ordinary chemical reaction

26
(No Transcript)
27
(No Transcript)
28
Law of Conservation of Mass

• Two Examples
• 1. 2H2 O2 ? 2H2O
• 10g 80g ? 90g
• 2. Burning wood ?
• Wood O2 ? Gas Ash

29
Law of Conservation of Energy

• Energy can never be created or destroyed. It can
  only change form.
• Battery turns chemical to electrical to
  mechanical energy.
• ALWAYS lose some energy in transformations
  (usually as waste heat)

30
Einstein1905

• Law of cons. of mass/energy mass and energy
  cannot be created or destroyed. They only change
  form
• 1. E mc2
• E Energy
• m mass
• c speed of light

31
Einstein1905

• 2. A small amount of matter can be destroyed to
  release a large amount of energy (nuclear
  processes) (20 g U ? 18 g U)

32
(No Transcript)
33

• Energy The capacity to do work
• 1 Joule 1 Newton-meter
• 1 calorie amount of heat to raise one gram of
  water by 1o C
• 1 calorie 4.18 Joule
• (1 nutritional Calorie 1000 calories, 1
  kilocalorie)

34

• Two types
• Stored (Potential Energy)
• Gravity Book on shelf
• Mechanical coiled spring
• Chemical Energy energy stored in chemical bonds
• Plants absorb energy from the sun
• That energy is released through digestion/burning

35

• Energy in use (Kinetic Energy)
• Moving baseball
• Water flowing through a hydroelectric plant
• Energy of moving atoms and molecules

36
Specific Heat

• Specific Heat Amount of heat needed to raise
  the temperature of one gram of a substance by one
  degree Celsius or Kelvin
• Unit cal/goC or J/goC
• Symbol Cp
• The higher the specific heat, the more energy
  needed to raise the temperature

37

• Predict the specific heat of the following (high
  or low)
• Car hood
• Pot of water
• Beach sand
• Plants Trees

38
Calculating Heat

• q mCpDT
• q heat in Joules
• m mass (grams)
• Cp specific heat (J/goC)
• DT Tfinal Tinitial

39

• How much heat must be supplied to a 500.0 gram
  iron pan (Cp 0.444 J/g oC) to raise its
  temperature from 20.0oC to 100.0oC?
• q mCpDT
• q (500.0g)(0.444J/g oC)(100.0oC -20.0oC)
• q (500.0g)(0.444J/g oC)(80.0oC)
• q 17,800J or 17.8 kJ

40

• Suppose we use a similar pan, except it is now
  made of Aluminum (Cp 0.895 J/goC)?
• q mCpDT
• q (500.0g)(0.895 J/goC)(100oC -20oC)
• q (500.0g)(0.895 J/goC)(80oC)
• q 35,800 J or 35.8 kJ

41
What temperature change would 50.0 g of rock
undergo if they absorbed 452 Joules of heat?
(Assume the specific heat is 0.836
J/goC).) ANS 10.8 oC (which is also 10.8 K)
42
Heating Curves

• Changes of state do not have a temperature
  change.
• Melting/Freezing
• Boiling/Condensing
• A glass of soda with ice will stay at 0oC until
  all of the ice melts.
• Graph flattens out during changes of state

43
Steam heats up
Temperature (oC)
Boiling
Water warms up
Melting
Ice warms up
Heat (Joules)
44

• Calculate the square root of 57.2
• Calculate the cube root of 57.2
• Calculate the cube root of 144
• Calculate the 4th root of 625

45

• What is the volume of 0.0354 kg of gold?
• What mass of mercury would occupy 25.0 mL
• Which would have a greater mass, 50 mL of water
  (1g/mL) or 50 mL of vegetable oil (0.72 g/mL)
• A piece of zinc (7.14 g/cm3) has a mass of 257 g.
  If the zinc is rectangular and has a length of
  1.00 cm and a width of 4.00 cm, what is the
  height?
• A cylinder of copper (8.92 g/cm3) is found to
  have a mass of 1681 grams. If the cylinder is
  15.0 cm tall, what is the radius?