Substances, Mixtures, Solubility

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Substances, Mixtures, Solubility

• What is a Substance?

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Substance-
matter that has a fixed composition.
-cant be broken down by physical processes
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Physical -Boiling -Change
pressure -Cooling -Sorting
Chemical -Burning -Reacting with
chemicals -Reacting with light
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Examples of substances
Elements- Atoms of different kinds
- Different s of protons Ex. O, S, C, Fe, Au
etc. Compounds- Substances made of 2 or more
elements chemically combined - Fixed composition
(atomic ratios) Ex. H2O, NaCl ex. H2O is always
H2O not H3O or H2O2
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Mixtures-

• Made of 2 or more substances (mixed together)
• CAN BE separated physically
• CAN BE put together in any proportion

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2 Types of Mixtures

• Heterogeneous Mixture-
• different throughout
• Homogeneous Mixture-
• same throughout (solution)

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Solution-

• Evenly mixed on a molecular level but NOT bonded
  together
• Ex. Saltwater

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2 Parts of a Solution

• Solute gets dissolved
• Ex. salt
• Solvent- does the dissolving
• Ex. Water

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Types of Solutions

• Liquid Solutions

Gaseous Solutions
Solid Solutions
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Liquid Solution-

• A solution having a liquid solvent

-Solute can be
Solid salt water Liquid vinegar water Gas -
pop
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Gaseous Solution-

• 2 or more gases in solution
• Ex. Air

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Solid Solution-

• 2 or more solids in solution
• Ex. Steel Iron Carbon

-Melt it , Mix it, Coooooool it down
Alloy- 2 or more metals in solution Ex. Brass
Copper Zinc
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Solubility

• The Universal Solvent

WATER!!
Aqueous Solution -
A solution where water is the solvent.
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Molecular Compounds

• Compounds Chemically Bonded

- This means that they share electrons (Covalent
Bond)

• If the electrons are not shared equally the
  molecule is POLAR
• (has a - end)

Ex. H2O
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Ionic Bonds

• Ion -

Atoms with a charge (because theyve gained or
lost electrons)
-
Loses an electron
Gains an electron
e
Na
Cl -
Bonds Together (opposites attract)
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How Water Dissolves Ionic Compounds
-

H
O
H

-
Negative Ion

• Positive Ion

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How Water Dissolves Molecular Compounds

• H2O gets in between the molecules (separating
  them)
• Ex. Sugar (also a polar molecule)

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What Will Dissolve?

• Like Dissolves Like!!

-Polar molecules dissolve polar molecules
Ex. H2O sugar
- Nonpolar molecules dissolve nonpolar molecules
Oil Nonpolar H2O - Polar
they dont go into solution
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How Much Will Dissolve?

• Solubility-

Describes how much solute dissolves in a solvent
(at a given Temp).
(High Solubility - Lots of solute dissolves Low
Solubility Little solute dissolves Insolubile
Very little or NO solute dissolves)
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Rate of Dissolving

• - Speed it up by

1. Raise the Temperature
2. Stirring
3. Crush the Solute
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1. Raise the Temperature

• Increases molecule movement
• Mix faster

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2. Stirring

• - Puts fresh solvent in contact with solute

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3. Crush the Solute

• Exposes more surface to solvent
• More solvent contact

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Making Solutions

• Dilute
• Concentrated
• Saturated

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Dilute -

• Describes a solution made by dissolving a small
  amount of solute in a large amount of solvent.

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Concentrated -

• -Describes a solution made by dissolving a large
  amount of solute in a solvent.

-may be a limit at a certain temperature
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Saturated -

• -Describes a solution that has all the solute
  that it can hold without changing conditions.

Temp. amount of solute
SUPER SATURATED
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Acidic Basic Solutions

• Acids-

Substances that release positively charged
hydrogen ions (H) in water.
H combines with H2O H3O
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Properties of Acids

• 1. Sour taste NEVER TASTE
• 2. Conducts electricity ex.Battery acid
• 3. Corrosive- can break down certain substances
  ex. Fabric, paper, skin
• 4. Solutions can react strongly with some metals

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Uses Acid

• Salad dressing acetic acid
• Citrus fruits citric acid
• Vitamin C ascorbic acid
• Ants formic acid
• Pickling, steal, paint, sulfuric acid
• Fertalizers, plastics sulfuric acid
• Cleaning hydrochloric acid
• Fertilizers, dyes, nitric acid
• plastics

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Acids and the Environment

• Cave formation Carbonic Acid
• ( CO2) in the soil is dissolved in H2O)
• - Can dissolve limestone (calcium carbonate)

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Acids and the Environment

• ACID RAIN

1. Sulfur dioxide and nitrogen oxides are released
   into the air - power plants etc.
2. These react with H2O in the air to form nitric
   acid and sulfuric acid
3. When it rains Acid Rain

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Acidic Basic Solutions

• Bases-

Substances that accept hydrogen ions (H).
When bases dissolve in H2O
H2O looses H OH - hydroxide ion

O
H
O
-

H
H
H
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Properties of Bases

• 1. Bitter taste NEVER TASTE
• 2. Feels slippery - soap
• 3. Corrosive- can break down certain substances
  ex. Burns, tissue damage
• 4. Contains ions
• - Conducts electricity
• - does not react with metals like acids

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Uses Base

• Soaps OH- interacts strongly
• Cleaning products with dirt and grease.
• Oven cleaner ex. Lye sodium hydroxide
• Chalk
• blood
• Lime - CaOH - marks lines on sports fields

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What is pH?

• pH- a measure of how acidic or how basic a
• solution is.

Basic
Acidic
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Most Acidic Ex. Hydrochloric Acid (HCL)
Most Basic Ex. Sodium Hydroxide (NaOH)
Neutral
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The pH scale-

• One pH unit represents a TENFOLD change in the
  acidity

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
100 x more basic
10 x more acidic
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Strengths of Acids Bases

• The weaker the acid, the higher the pH ex. Food
• The stronger the acid, the lower the pH
• ex. Dangerous burns

Basic
Acidic
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Neutral
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-The strength is related to the number of H ions
it donates

• Hydronium ions H3O Acid strength

• Lower pH

• H donated

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Indicators-

• Compounds that react with acidic or basic
  solutions producing certain colors depending on
  the solutions pH.

Ex. Cabbage Juice

• Ex. Litmus soaked into paper strips

• Turns --- RED in Acid
• --- BLUE in Base

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Neutralization-

• The interaction between H of an acid and OH- of
  a base to form H2O and salt.

Ex. Antacid (Magnesium Hydroxide (Mg(OH)2)

• How Neutralization Occurs

• H3O OH- 2 H2O

H
O
H
H
O
O
O
H
H
H
H
pH 7 neutral
H