Chapter 2 Chemistry
What is a difference between chemical change and physical change?
-A chemical change the composition of matter always changes. Ex. rust -A physical change the composition of matter never changes. Ex. Boiling, freeze, melt, condense, break, split, grind, cut, and crush
Chemical Reaction
-Also known as a chemical change -One or more substances change into one or more new substances
How do you tell the difference between substances and mixtures?
-If the composition of a material is fixed, the material is a substance -If the composition of a material may vary, the material is a mixture
What are some characteristics about gases?
-Particles are farther apart -Gases are easily compressed into a smaller volume -Substances exist in the gaseous states are at room temperature
What are some characteristics about liquids?
-Particles in liquids are in close contact with one another but are not rigid or orderly -Particles are free to flow -Take the shape of the container -The volume doesn't change
Chemical Property
-The ability of a substance to undergo a specific chemical change Ex. Iron is able to combine with oxygen to form rust
What are some characteristics about solids?
-They are almost in-compressible -Expand only slightly when heated -Particles in a solid are packed tightly together and arranged orderly
How can you tell whether a chemical change has taken place?
-Transfer of energy -Change in color -The production of a gas -The formation of a precipitate
Solid
A form of matter that has a definite shape and volume.
What happens during a distillation?
A liquid is boiled to produce a vapor that is then condensed into a liquid. (This is to separate water from other substance such as the ones in tap water)
Mixture
A physical blend of two or more components Ex. chicken noodle soup (chicken, noodles, and broth), air
Physical Property
A quality or condition of a substance that can be observed or measured without changing the substance's composition Ex. hardness, color, state, conductivity, and malleability
Reactant
A substance present at the start of the reaction
Product
A substance produced in the reaction
What do chemists use to represent elements and chemical formulas to represent compounds?
Chemical symbols
Heterogeneous Mixture
Composition is not uniform throughout Ex. chicken noodle soup (more chicken in one spoonful than in another spoonful)
Phase
Describes any part of a sample with uniform composition and properties
Law of Conservation of Mass
In any physical change or chemical reaction, mass is conserved. Mass can neither be created nor destroyed.
Chemical Change
Is a change that produces matter with a different composition that the original matter Ex. Heating or Electricity
Liquid
Is a form of matter that has an indefinite shape, flows, yet has a fixed volume
Gas
Is a form of matter that takes both the shape and volume of its container
Homogeneous Mixture
Is a mixture in which the composition is uniform throughout. Ex. Olive oil and Vinegar
Extensive Property
Is a property that depends on the amount of matter in a sample Ex. Mass and Volume
Intensive Property
Is a property that depends on the type of matter in a sample, not the amount of matter Ex. bowling ball hardness and texture
Precipitate
Is a solid that forms and settles out of a liquid mixture Ex. the ring of soap scum around a bathtub
Compound
Is a substance that contains two or more elements chemically combined in a fixed proportion Ex. carbon, oxygen, and hydrogen are chemically combined in the compound sucrose
Element
Is the simplest form of matter that has a unique set of properties Ex. Oxygen and Hydrogen
Substance
Matter that has a uniform and definite composition Ex. gold and copper
Can elements be broken down?
No, but compounds can be.
How many phases do homogeneous mixtures consist of?
One
Filtration
Process that separates a solid from the liquid in a heterogeneous mixture
What are physical changes classified as?
Reversible and irreversible Ex. Melting
What is another name for homogeneous mixtures?
Solution
Physical Change
Some properties of a material change, but the composition of the material does not change Ex. Boiling, freeze, melt, condense, break, split, grind, cut, and crush
What does the mass of the products equal?
The mass of the reactants
How many phases do heterogeneous mixtures consist of?
Two or more
Can a mixture be heterogeneous or homogeneous?
Yes
What are some other examples of a physical change?
cutting hair, filing nails, and cracking an egg
What are examples of physical properties
hardness, color, conductivity, and malleability
