colloids grade 6 science presentationppt

ppt

1. CHAPTER 6.1
Solutions and Other Mixtures

2. Classifying Matter
•The composition of a
material can be used to
classify it as a mixture or a
substance
•The composition of a pure
substance is constant
•The composition of a
mixture can vary widely
Matter
Substance
Mixture
Element
HeterogeneousHomogeneous
Compound

3. Types of Mixtures
•Heterogeneous Mixture: The parts of the
mixture are noticeably different from one
another.
–Examples: Sand, Salsa, Chocolate Chip Cookie
Dough
•Homogeneous Mixture: The substances are so
evenly distributed that it is difficult to distinguish
one substance in the mixture from another.
–Examples: Swimming pool water, Stainless steel
fork

4. Solutions, Suspensions, & Colloids
•Mixtures can be
classified based
on the size of
their largest
particles.

6. Suspension
•Suspension –
•Settles out or separates into different
layers when it is no longer agitated
•(no longer moving).
•Heterogeneous mixture
•Separates into layers over time
•Particles can be trapped by filter
paper (like a coffee filter)
•Are cloudy in appearance
•Examples: Sand and Water

7. Filtration
•Separates materials
based on the size of
their particles
•Examples:
–Drip coffee makers
–Wire screens at an
archaeological site

8. Colloid particles are larger than the
particles in a solution.
•No, you don’t
need to learn
the exact sizes
of the particles,
just realize that
there is a
defined size.

9. Colloids
•Contain some particles that are intermediate in
size and are in between the small parts in a
solution, and the larger particles in a
suspension.
•They do not separate in layers
•You can’t use a filter to separate the parts of a colloid
•The scattering of light property can be used to
separate them from other mixtures

10. Colloids
•Particles are large enough to scatter light.
•That means that you actually see what we call a “beam
of light” – in a solution, which has really small particles,
the light passes right through.

12. Scattering of light

14. Slide #13 gives “opal” as an
example of a colloid. It’s a
gemstone, and here’s what it looks
like.

15. Emulsions
Liquid/liquid systems of 2 immiscible substances are called
emulsion. Substances or particle size = 10-100 microns.
Examples: butter (w/o), margarine (w/o), mayonnaise (o/w),
salad dressing (o/w), milk (o/w), cream (o/w), and chip-dip (o/w).
Water
Oil
OilOil
Oil
Oil
H O
H OH O
H O
Oil/Water Water/Oil
2 2
2 2
Oil
Oil Oil
Oil
Oil
Oil

16. Solutions
•Formed when substances dissolve and
form a homogeneous mixture
•Characteristics
–Do not separate into distinct layers over time
–Will not leave trapped substances when
poured through a filter
–Most are translucent (clear or see-through)

17. Solutions
•Solvent
•Substance that dissolves
the solute,
•stuff “doing the
dissolving.”
•Water in salt and water
•water in “sweet tea”
•What you have the most
of!
•Solute
•Substance that
dissolves in the
solution.
•Salt in the water
•Sugar in the tea
•Chemicals put in your
fish tank.

18. Using Properties to Separate Mixtures
Distillation & Filtration
are 2 common separation methods