4.1 Introduction for Reactions

homogeneous mixture

visibly indistinguishable parts

heterogeneous mixture

visibly distinguishable parts

pure substance

substance with one constant composition

compound

a substance with constant composition that can be broken down into elements by chemical process

elements

substance that cannot be decomposed into simpler substances by chemical or physical means

physical change

physical property of a substance changes without changing the composition

distillation separates substances based on ____

boiling points

filtration separates substances based on _____

particle size

chromatography separates substances based on

inter-molecular forces

examples of physical changes

separations of mixtures, making solutions, deformation

True or False: Physical changes are usually reversible

True

evidence of chemical reactions

production of percipitate, color change, light, temp change, sound, production of gas, new substances

Composition synthesis (AB)

A + B → AB

Decomposition (AB)

AB → A + B

Single Ionic replacement (ABC)

A + BC → AC + B

Double ionic replacement (ABCD)

AB + CD → AD + CB

Combustion of a hydrocarbon (or a metal)

Hydrocarbon:

C_xH_y + O₂ → CO₂ + H₂O

Metal:

M + O₂ → M_xO_y