ch. 8 - chemical equations and reactions Flashcards
chemical reaction
process by which one or more substances are changed into one or more different substances
law of conservation of mass
the total mass of reactants must equal the total mass of products for any given chemical equation
chemical equation
representing, with symbols and formulas, the identities and relative molecular or molar amounts of the reactants and products in a chemical reaction
indication of a chemical reaction
- evolution of energy as head or light
- production of gas/odor
- formation of a precipitate
an equation gives no indication of…
- whether a reaction will actually occur
- the speed at which it will occur
- how the bonding between atoms or ions change during reactions
synthesis reaction
two or more substances combining to form ONE new compound
A + X –> AX
decomposition
a single compound undergoes a reaction to produce two or more simpler substances
AX –> A +X OR AB + O –> AO + BO
electrolysis
decomposition of substances by an electric current
single displacement (/replacement)
one element replaces a similar element in a compound
A + BX –> AX + B OR Y + BX –> BY + X
- many take place in aqueous solutions
- metal = A + BX –> AX + B (replaces first one)
- nonmetal = Y + BX –> BY + X (replaces second one)
combustion
a substance combines with oxygen, releasing a large amount of energy in the form of light and heat
- the combustion of ANY hydrocarbon (consisting of hydrogen and carbon) and oxygen ALWAYS yields CO2 and H2O
up arrow
gas forms
down arrow
precipitate forms
–> with triangle on top
heat applied
two opposite facing arrows in the form of an equal sign
reversible action
aq
aqueous – dissolved in water
activity
the ability of an element to react
- the more readily an element reacts with other substances, the greater its activity is
activity series
a list of elements organized according to the ease with which they undergo certain chemical reactions
- metals: greater activity means it loses electrons easier to form positive ions
- nonmetals: greater activity means it gains electrons easier to form negative ions
precipitate
a solid produced as a result of a chemical reaction that separates from the solution
- in a solution with two aqueous reactants, if one of the products is a solid, it is a precipitate!
