Title: Mixtures and Solutions
1Mixtures and Solutions
- Diane Gioia
- Bells Crossing Elementary
2What is a mixture?
- A mixture is two or more substances that are
mixed together but not chemically combined. - The substances in a mixture each keep their own
properties, and they can be separated into their
original form. - A bag of snack mix can be separated into raisins,
walnuts, peanuts, etc.
3Examples of mixtures
- Vegetable salad
- Fruit salad
- Mixture of sand, water, and marbles
- Mixture of sand and iron filings
4- Mixtures can be separated based on physical
properties. - Blood is a mixture of proteins, sugar, oxygen,
carbon dioxide, and other substances. The
different substances in blood can be separated
based on their densities.
5What are Solutions?
6Solutions
- Solutions are composed of substances that mix so
completely that they cannot be distinguished as
separate substances. - They can, however, be easily separated back into
the separate substances. - A solution is usually a mixture of a solid that
dissolves completely in a liquid. - Ex. Sugar in water
7Solutions
- A solution is a special kind of mixture.
- The substances in a solution dissolve, or
separate into their most basic particles. - The particles of one substance are spread evenly
through another. - The substances in a solution can be solids,
liquids, or gases.
8Examples of a Solution
- Carbon dioxide bubbles in a soda.
- Carbonated water mixed with lemonade is a
solution of solids, liquids, and gases. - Lemon juice, water and sugar crystals. Sugar is
the solid, lemon juice is the liquid dissolved
together in water.
9What makes up a solution?
- In a solution, the substance that dissolves is
called the solute. - The solvent is the substance in which the solute
is being dissolved. - Sugar is the solute and water is the solvent.
- Water is considered the universal solvent.
10True or False?
- All solutions are mixtures, but not all mixtures
are solutions.
11TRUE!
- That's a true statement. All solutions are
mixtures. They are defined as homogeneous
mixtures. Solutions might include salt water,
soda water, or even metal alloys. Not all
mixtures are solutions. If you mix sand and
water, you might have a liquid involved, but that
doesn't make it a solution. A mixture that
includes sand and water would be defined as a
heterogeneous mixture. The parts are not
distributed evenly throughout the system.
12Why is the Venn Diagram combined with the
solution circle within the mixture circle?
- Explain in your journal. Summarize with class.
MIXTURES
Mud chex mix Fruit salad
SOLUTIONS
Salt water lemonade soda
p.s. Mud is a special mixture called a
suspension. The particles suspend in the water.
13Can you make a list of Mixtures?
14How many Solutions can you list?
15How do we separate mixtures and solutions?
- There are many ways to separate mixtures and
solutions. - The method depends on the properties of the
different materials in the mixture.
16Make a Lotus
How can you separate the materials in mixtures
and solutions?
17SIFTING
- One way to separate the larger materials from the
smaller ones is by sifting. - Sifting allows smaller materials to pass through
holes leaving the larger materials behind. - How would you use sifting to separate marbles,
safety pins, sand, and salt?
18Magnetic Attraction
- After you have separated the sand and salt from
the bigger materials using sifting you can use
a magnet to pick up the objects made out of
certain metals such as paper clips and safety
pins. - Could you use a magnet to separate
- Sand, marbles, and plastic beads?
- Why or why not?
19Floatation
- Floatation is using a liquid to separate
materials of different densities. - A material that is less dense will float on a
material that is more dense. - Plastic beads are less dense than marbles.
- How would you separate marbles from plastic beads
using floatation?
20Filtration
- You can also separate solutions by filtering
them. Filtration is separating solids from
liquids by passing a mixture through a filter. - Salt dissolves in water while sand does not.
- How could you separate salt and sand using water
and a filter?
21Evaporation
- After you have filtered out the sand from the
solution of salt water, you can use evaporation
to separate the salt from the water. - When water evaporates from the mixture, solid
salt particles will be left behind. - How would evaporation naturally separate dirt
from water in a mud puddle?
22Chromatography
- Chromatography separates solutions by dissolving
them in special liquids.
For example, chromatography can be used to
separate substances such as pigments in a leaf
like in the picture. The police department uses
chromatography to separate and identify all kinds
of substances.
23How can we make a solution more or less
concentrated?
- The concentration of the solution is a measure of
the amount of solute compared to the amount of
solvent. - If the amount of solute is small compared to the
amount of solvent, the solution is said to be
dilute. - If the amount of solute is large compared to the
amount of solvent, the solution is said to be
concentrated.
24Concentrations
- For example, if you took one gram of salt and
added it to 100 grams of water, the solution is
dilute. - If the same amount of water has 30 grams of salt,
the solution is concentrated.
25Rate of Dissolving
- You know that salt easily mixes with water by
dissolving in it. But did you know that salt can
dissolve at different rates? - The temperature of the water, the size of the
salt particles, and how you stir the solution are
factors that affect how quickly the salt
dissolves.
26Temperature
- Temperature affects the rate of dissolving in a
solution. - The particles of a substance are always moving.
When heat is added, the particles move faster
making it dissolve faster in a liquid. - Think about adding sugar to ice tea vs. hot tea.
Which one dissolves faster?
27Particle Size
- Another factor that affects the rate of
dissolving is particle size. The smaller the
solute particles are, the faster they dissolve. - If you have ever made a cup of hot chocolate, you
dissolved powder into milk. - If you put a piece of a chocolate bar in the
milk, it would take a longer time to dissolve.
28Stirring
- Stirring also affects the rate of dissolving.
-
- When adding particles to a liquid, you stir or
shake the liquid. This action makes the solute
dissolve more quickly. - What happens if you pour a drink mix into a
container without stirring?
29Solubility
30Chemical ReactionsLet's start with the idea of
a reaction. In chemistry, a reaction happens when
two or more molecules interact and something
happens. That's it. What molecules are they? How
do they interact? What happens? Those are all the
possibilities in reactions. The possibilities are
infinite.
31A few key points
- A chemical change must occur. You start with one
compound and turn it into another. That's an
example of a chemical change. A steel garbage can
rusting is a chemical reaction. That rusting
happens because the iron (Fe) in the metal
combines with oxygen (O2) in the atmosphere.
32- When a refrigerator or air conditioner cools the
air, there is no reaction. That change in
temperature is a physical change. Nevertheless, a
chemical reaction can happen inside of the air
conditioner.
33Another chemical reaction
34How is a chemical change different from a mixture?
- A compound is a type of matter made of a
combination of elements. In a compound, two or
more elements are combined chemically. - Water is made up of two atoms of hydrogen and one
atom of oxygen. - H20
35- The proportion of hydrogen and oxygen atoms in
water is always the same. - If the proportion of elements in a compound is
changed, a new compound is formed. - Both water and hydrogen peroxide are made of
hydrogen and oxygen atoms. - However, a molecule of hydrogen peroxide contains
two hydrogen atoms and two oxygen atoms. - Hydrogen peroxide is NOT like water and you
should not drink it. - H2O2
36Separating Compounds
- When elements combine chemically, they form
compounds with properties that are different from
the properties of the individual elements. - These elements cannot be easily separated like in
a mixture.
37- A chemical change occurs when atoms link together
in new ways to create a substance different from
the original substance. This is a chemical
reaction.
38Signs of a Chemical Change
- Changes color
- Forms tarnish
- Releases gas
- Forms a precipitate
- Releases energy
39Matter and its Properties
- Full video 1706
- ( a good review
- or watch segment on chemical reactions
153)