Matter and Properties

1
Matter and Properties

• Solubility and Solutions

2
Scientific Method

• State the problem
• Gather info through questioning
• Form a hypothesis
• Gather and analyze data
• Draw conclusions
• Make a prediction

3
Experiments

• Experiments contain
• Variables
• Dependent value changes according to changes in
  the independent (what am I measuring?)
• Independent variable you change to see how it
  affects the dependent
• Constant variable that doesnt change
• Controls
• standard to which others are measured

4
Experiment Example

• Your want to see how fertilizer affects plant
  growth on 4 plants. Plant 1 gets ½ cup, plant
  2 gets 1 cup, plant 3 gets 2 cups, plant 4
  gets none. The amount of water, sunlight, and
  type of soil was kept the same for all plants.
• Dependent variable
• Independent variable
• Constant variables
• Control

5
Scientific Law vs. Theory

• Law
• statement of what seems to be true all the time
• Law of Gravity
• Theory
• an explanation of things based on knowledge
  gained from observations and investigations
• not a guess
• Big Bang Theory

6

• Mass amount of matter in an object
• Volume amount of space an object takes up
• Length distance between two points

7

• Density mass per unit volume
• Objects mass divided by objects volume
• mass / volume

• Volume
• v l x w x h
• Solid m³, cm³
• Liquid mL, L

8
Base Units of Measurements
9
Common SI prefixes
10
Review Questions

• 1. If you were measuring the mass of some object,
  what unit of measurement would you use?
• 2. If you were measuring the volume of a liquid,
  what unit of measurement would you use?
• 3. Convert 50 mL ______ hm
• 4. Convert 2.1 km ______ dm

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Review Questions

• 5. An object has a volume of 5 mL and a mass of
  2 grams. What is its density?
• 6. A box has a length of 2 mm and a width of 1 mm
  and a height of 5 mm. What is its volume?
• 7. A cereal box has a volume of 50 cm³, a height
  of 10 cm, and a width of 1 cm. What is its
  length?

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States of Matter

• Kinetic Theory
• All matter is composed of particles
• These particles are in constant motion
• These particles collide with each other and the
  walls of their container

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States of Matter

• Solids
• Particles are closely packed
• Particles motion is slow (vibrating in place)
• Definite shape and volume

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• Liquids
• Particles are moving more freely
• No definite shape but definite volume

15

• Gases
• Particles are far apart
• No definite shape or volume

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Properties of Liquids

• Melting Point temp at which a solid becomes a
  liquid
• Heat of fusion energy required to change a
  substance from solid phase to liquid phase

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Properties of Gases

• Boiling Point temp at which liquid vaporized or
  becomes a gas
• Heat of Vaporization amount of energy required
  for liquid to reach its boiling point

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Thermal Expansion

• Thermal Expansion
• Increase in the size of a substance when the
  temperature is increased

19

• Buoyancy
• ability of a fluid to exert an upward force on an
  object immersed in it.
• Archimedes Principle

20
Buoyancy
21
Charless Law

• As temperature of gas is lowered, volume of gas
  decreases

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Dissolving

• 1.Add solute to solvent.
• 2.The solute and solvent interact with each
  other until the concentration of the two
  substances is equal throughout

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Dissolving of NaCl
Timberlake, Chemistry 7th Edition, page 287
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Solubility

• Solubility
• maximum grams of solute that will dissolve
• in 100 g of solvent at a given temperature
• varies with temp
• based on a saturated solution

25
Solubility
increasing concentration
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Solubility Table
Solubility vs. Temperature for Solids
140
KI
130
120
NaNO3
110
100
KNO3
90
80
HCl
NH4Cl

• shows the dependence
• of solubility on temperature

70
Solubility (grams of solute/100 g H2O)
60
NH3
KCl
50
40
30
NaCl
KClO3
20
10
SO2
0 10 20 30 40 50 60 70 80 90 100
LeMay Jr, Beall, Robblee, Brower, Chemistry
Connections to Our Changing World , 1996, page
517
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Solubility

• Solids are more soluble at...
• high temperatures.

• Gases are more soluble at...
• low temperatures
• high pressures (Henrys Law).
• EX nitrogen narcosis, the bends, soda

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Solids dissolved in liquids Gases dissolved in
liquids
As To , solubility
As To , solubility