Reactions

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Synthesis: making something new, building "blocks" to make something bigger A+B->AB

Decomposition: Electrolysis, get broken down, larger molecule to smaller, AB->A+B

Single Displacement: Placing it somewhere else, the two metals are trading places, it is always the positive ion that is replaced, A+BC -> AC+B

Double Displacement: 2 metals trade places, new compound with different metals, AB+CD->AD+CB

Complete combustion: fuel burn cleanly with no sooty residue, CxHy + O2 -> Co2 + H2O, blue flame

Incomplete combustion: CxHy + O2 -> CO2 + H2O +CO + C, orange, flickery flame

Conservation of Mass

The law of conservation of mass is that during a chemical reaction, the total mass of the reactants is always equal to the total mass of the products

During chemical reaction, atoms are not changed but simply rearranged.

Molecules may be broken apart and new molecules formed

A skeleton equation shows the chemical formula for all molecules involved, but is imbalanced

An equation is balanced if there are an equal number of atoms on both sides of the equation (reactants and products)

Combustion reactions are chemical reactions in which a fuel burns/reacts quickly with oxygen

the products of combustion depend on the availability (amount of ) oxygen present

Complete combustion: hydrocarbons(fossil fuels) burn completely to release the energy they contain and form water and carbon dioxide as their products

Hydrocarbon+oxygen->carbon dioxide + water + energy

During complete combustion fuels burn cleanly with no sooty residue.

Incomplete combustion: -if the amount of oxygen is limited, other products form, such as carbon monoxide (a toxic gas) and soot (made up of particles of carbon)

H2O+CO+C+CO2+energy

State Symbol:

Chemical reactions describe both the reactants and the product

State of these must be also given in a chemical reaction

(s) for solid e.g. metals and ionic compounds not in solution

(l) for liquid e.g.water

(g) for gases e.g. O2, N2

(aq) aqueous, for chemicals dissolved in water, e.g. inonic compounds when in solution. NaCl, acids, base

These are written as subscripts beside the chemicals in a chemical equation

Reaction Types

Conservation of Mass

Combustion

Describing states in chemical reaction