Physical Changes
A change in appearance but keeps the same identity
If you spill a jar of coins and marbles, what property could you use to separate them quickly
Size/shape and color
A chemical change is different from a physical change because
A chemical change produces a new substance, while a physical change does not.
The law of conservation of mass states
Matter is not created or destroyed in a chemical change.
Milk is an example of this type of mixture.
Colloid
Freezing water into ice considered a physical change because
The substance is still water, only its state changes.
True or False: A magnet separating iron from sand is using a CHEMICAL property to separate mixtures
False
Burning something count as a chemical change because
Energy is released?
Why does the mass of reactants always equal the mass of products?
Because atoms are rearranged, not lost or gained.
True or False: Mouthwash is an example of a homogenous mixture
True
True or False: Physical changes alter the chemical identity of a substance.
False
Two liquids with different boiling points can be separated in this way
Distillation
The most reliable proof that a chemical change has taken place
Is it the formation of a new substance
Why does it sometimes look like matter disappears in a chemical reaction
Because gases may be formed and aren't measured
The difference between a suspension and colloid is:
particles in a suspension settle, colloid particles never settle
Tearing paper or chewing gum count as a physical change because
Only the size and shape change
Magnetism a reliable property for identifying certain metals because
It is specific to only magnetic metals
Name two common signs that a chemical change has occurred.
color change, energy release, gas formation, precipitate formation.
Why is the presence of a solid forming in a liquid strong evidence of a chemical reaction?
Because it means a new substance has formed.
The scattering of light in a colloid is called:
The Tyndall Effect
Name two physical properties that remains the same whether iron is a solid or a liquid.
Density, melting point, boiling point, or magnetism
Separating mixtures often easier than separating compounds because
Mixtures can be separated by physical means, while compounds cannot
Chemical changes usually harder to reverse than physical changes because
Do they rearrange atoms into new substances
Why is digesting food an example of a chemical change?
Because food is broken down into new substances that the body can use.
What is the main difference between a compound and a mixture
Compounds have a fixed composition; mixtures can vary and be separated physically