CW3 Chemical reactions involve rearranging atoms to form new substances; during a chemical reaction mass is not created or destroyed

Decomposition reaction

complex compound breaks down into simpler compounds where AB → A + B

polyatomic

containing more than one and especially more than two atoms

rate of reaction

the speed at which a chemical reaction proceeds

Base

a substance that can neutralize the acid by reacting with hydrogen ions

Aerobic respiration

A chemical process in which oxygen is used to make energy from carbohydrates (sugars).

Alkali

A chemical that can dissolve in water, combine with acids to form salts, and make acids less acidic

Neutralisation formula

Acid + Base (Neutralisation reaction) -> Salt + Water

endothermic

Chemical reactions that absorb (or use) energy eg. photosynthesis, melting ice, evaporating liquids

Combustion and equation

Combustion is the burning of fuel in oxygen to provide heat energy. Fuel + O2 -> CO2+H2O +Heat energy

compound

a substance made up of two or more different chemical elements combined in a fixed ratio

enzyme

a biological catalyst and is almost always a protein

Acid

a contributing product containing hydrogen ions

molecule

a group of two or more atoms held together by chemical bonds

Atom

a particle of matter that uniquely defines a chemical element

precipitate

a precipitate is an insoluble solid that emerges from a liquid solution

exothermic

a reaction in which energy is released in the form of light or heat eg. nuclear fission, rusting iron, combustion

Anion

an atom that has more electrons than protons (negative charge)

cation

an atom that has more protons than electrons (positive charge)

Anodising

an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish

catalyst

any substance that increases the rate of a reaction without itself being consumed

ion

atoms that bears one or more positive or negative electrical charges

respiration

biochemical process in which the cells of an organism obtain energy by combining oxygen and glucose

law of conservation of mass

in a chemical reaction mass is neither created nor destroyed

pH

quantitative measure of the acidity or basicity of aqueous or other liquid

Precipitation and equation

reactions occur between two aqueous compounds and form a precipitate (solid) and an aqueous solution AB (Compound 1) + CD (Compound 2) -> AD (Precipitate) + BC (Aqueous)

Acid + Metal

salt + hydrogen gas

Acid + Carbonate

salt + water + carbon dioxide

indicator

substances whose solutions change color due to changes in pH eg. Litmus

concentration

the amount of a substance present in a mixture

Corrosion

the gradual destruction of metals due to electrochemical reactions with their surroundings, typically water, salt water or air.

Agitation

the movement of one or more components of a mixture to improve contact

chemical digestion

the process of further degrading the molecular structure of the ingested compounds

combination reaction (synthesis)

when two or more reactants unite to generate a single product