Mixtures, Solutions, Acids, and Bases
Mixtures, Solutions, Acids, and
Bases
Mixtures, Solutions, Acids, and Bases
Mixtures
•Two or more substances (elements and/or compounds)
combined but NOT chemically
–each substance keeps its properties
–Can be separated by physical properties
•Example: salt, sand, and water
Mixtures, Solutions, Acids, and Bases
Heterogeneous mixture
•“Not well mixed”; different parts
–Parts can be easily separated
•Salad
Mixtures, Solutions, Acids, and Bases
Homogeneous mixture
•“Well mixed”
–So well mixed that parts are difficult to separate
•Cake batter
•Video Heterogeneous or homogeneous?
- Understanding
Solutions
Mixtures, Solutions, Acids, and
Bases
What Is a Solution?
Two parts to solutions:
Solute: part being dissolved
Solvent: part doing the dissolving
A solution has the same properties throughout. It contains solute particles
(molecules or ions) that are too small to see.
Mixtures, Solutions, Acids, and Bases
What Is a Solution?
Solutions can be made from any combinations of solids,
liquids, and gases.
Mixtures, Solutions, Acids, and Bases
- Understanding Solutions
Colloids and Suspensions
Colloids and suspensions are mixtures that have physical
properties different from those of solutions.
Colloid: small undissolved particles that never settle (permanently
suspended)
Suspension: particles settle out or can be filtered to separate
Mixtures, Solutions, Acids, and Bases
Particles in a Solution
When a solution forms, particles of the solute leave each
other and become surrounded by particles of the solvent.
Mixtures, Solutions, Acids, and Bases
Salt Dissolving in Water Activity
Click the Active Art button to open a browser window and
access Active Art about salt dissolving in water.
Mixtures, Solutions, Acids, and Bases
Effects of Solutes on Solvents
At 0ºC, pure water freezes, but water mixed with a solute
does not. Solutes lower the freezing point of a solvent.
Solid (frozen) water
Liquid water solution
Mixtures, Solutions, Acids, and Bases
Pure water boiling
Pure water boils at _______
degrees C?
Salt Water Boiling
Salt water boils at _______
degrees C.
Mixtures, Solutions, Acids, and Bases
Identifying Main Ideas
Main Idea
A solution is a well mixed mixture that contains a solvent
and at least one solute.
Detail
Detail
Detail
The solvent is
the substance
present in the
largest
amount.
A solute is a
substance
present in a
smaller
amount than
the solvent.
A solution has
the same
properties
throughout.
Detail
A solution
contains
particles that
are too small
to see.
Mixtures, Solutions, Acids, and Bases
Universal Solvent
Click the Video button to watch a movie about
universal solvent.
Mixtures, Solutions, Acids, and Bases
Concentration
Amount of solute in a certain amount of solvent
Concentrated: a lot of solute in solvent
Dilute: a little solute in solvent
Two ways to describe concentration:
–Saturated: maximum amount of solute that can be
dissolved
•more solute will form a precipitate
–Unsaturated: less solute than could be dissolved
•Weak or dilute solutions
–Very little solute dissolved
- Concentration
and Solubility
Mixtures, Solutions, Acids, and
Bases
Solubility
Solubility is a measure of how
much solute can dissolve in a
solvent at a given
temperature.
•A physical property used to
identify substances
–Solubility curves
Soluble: solutes that can
be dissolved
Insoluble: solutes that will
NOT dissolve in the solvent
Mixtures, Solutions, Acids, and Bases
Which substance will
dissolve exactly 100
grams of solute at 45
◦C?
If you have 60g of
Sodium Nitrate
dissolved at 20°C, how
much more of the salt
will you have to add to
make a saturated
solution?
- Concentration
and Solubility
Mixtures, Solutions, Acids, and
Bases
Temperature and Solubility
The solubility of the compound
potassium nitrate (KNO3) varies
in water at different
temperatures.
- Concentration
and Solubility
Mixtures, Solutions, Acids, and
Bases
Temperature and Solubility
Reading Graphs:
At which temperature shown
in the graph is KNO3 least
soluble in water?
KNO3 is least soluble at 0ºC.
- Concentration
and Solubility
Mixtures, Solutions, Acids, and
Bases
Temperature and Solubility
Reading Graphs:
Approximately what mass of
KNO3 is needed to saturate a
water solution at 40ºC?
Approximately 65 g of KNO3
are needed to saturate a
water solution at 40ºC.
- Concentration
and Solubility
Mixtures, Solutions, Acids, and
Bases
Temperature and Solubility
Calculating:
About how much more
soluble is KNO3 at 40ºC than
at 20ºC?
KNO3 is about twice as
soluble at 40ºC as it is at
20ºC.
- Concentration
and Solubility
Mixtures, Solutions, Acids, and
Bases
Temperature and Solubility
Interpreting Data:
Does solubility increase at the
same rate with every 20ºC
increase in temperature?
Explain.
No; the curve shows that
solubility increases more with
each 20ºC increase in
temperature.
Mixtures, Solutions, Acids, and Bases
Links on Solubility
Brainpop on mixtures vs. compounds
Mixtures, Solutions, Acids, and Bases
Acid
Any substance that produces hydrogen ions (H+) when
it dissolves. The chemical formula for acids start with
“H”
Mixtures, Solutions, Acids, and Bases
Acid
Properties
•Taste sour
•React actively with metals
Mixtures, Solutions, Acids, and Bases
Acids
Strong
Hydrochloric
(stomach acid)
Sulfuric
(battery acid)
Weak
Carbonic
(carbonated drinks)
Citric
(citrus fruits)
Mixtures, Solutions, Acids, and Bases
Base
Any substance that produces hydroxide ions
(OH-) when it dissolves. The chemical
formula for bases end in “OH.”
Mixtures, Solutions, Acids, and Bases
Base
Properties
•Taste bitter
•Slippery to the touch
•Reacts with hair, etc. to remove clogged sinks
Mixtures, Solutions, Acids, and Bases
Base
Strong
Sodium hydroxide
(drain cleaner)
Potassium hydroxide
(in soft soap)
Weak
Ammonium hydroxide
(household cleaner)
Aluminum hydroxide
(anti-perspirants)
Mixtures, Solutions, Acids, and Bases
Acids and Bases in Solution
The table lists some commonly encountered acids and
bases.
Mixtures, Solutions, Acids, and Bases
The pH Scale
A low pH tells you that the
concentration of hydrogen ions is
high. In contrast, a high pH tells
you that the concentration of
hydrogen ions is low.
Mixtures, Solutions, Acids, and Bases
Indicators
Compounds which change color
when mixed with an acid or base.
Mixtures, Solutions, Acids, and Bases
Properties of Acids and Bases
Litmus is an example of an indicator, a compound that
changes color when in contact with an acid or a base.
Mixtures, Solutions, Acids, and Bases
Litmus
Red (pink) in acid.
Blue in base.
Mixtures, Solutions, Acids, and Bases
Phenolphthalein
Colorless in acid.
Pink in base.
Mixtures, Solutions, Acids, and Bases
Hydrion Paper
Use color scale.
Red in acid to dark green in base. Shows
pH.
Mixtures, Solutions, Acids, and Bases
pH
Brainpop on Acids and Bases
Click the Video button to watch a movie about pH.
Mixtures, Solutions, Acids, and Bases
Acid-Base Reactions
A reaction between an acid and a base is called neutralization.
An acid-base mixture is not as acidic or basic as the individual
starting solutions.
•When acids and bases react a salt is formed
Mixtures, Solutions, Acids, and Bases
Acid-Base Reactions
Each salt listed in this table
can be formed by the
reaction between an acid
and a base.
Mixtures, Solutions, Acids, and Bases
Uses of Acids and Bases
Acids and bases have many uses around the home and in
industry.
Mixtures, Solutions, Acids, and Bases
Strength of Acids and Bases
Strong acids and weak acids act differently in water.
Hydrochloric acid is a strong acid. Acetic acid is a weak acid.
Mixtures, Solutions, Acids, and Bases
What Is Digestion?
Chemical digestion breaks large molecules into smaller ones.
Mixtures, Solutions, Acids, and Bases
pH in the Digestive System
Foods are exposed to several
changes in pH as they move
through the digestive system.
Mixtures, Solutions, Acids, and Bases
Graphic Organizer
Solutions
are made of
Solutes
Solvents
dissolve in
dissolve to form
Ions
Molecules
conduct
do not conduct
Electricity
such as
Water