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