10. Chemical Reactions Flashcards
define a chemical change
changes within a substance where new substances with different MOLECULAR compositions and CHEMICAL PROPERTIES are formed
define a physical change
change to a substance that doesn’t affect its chemical structure or its composition
list some indicators of chemical change
- temperature changes
- formation of a solid (precipitate) in a solution
- production of an odour
- production of a gas
define a synthesis reaction and provide an equation
synthesis = A + B = AB
a reaction where two or more simple substances combine to form a more complex substance
when bonds form, is energy absorbed or released?
released
therefore, is a synthesis reaction exothermic or endothermic
exothermic
define a decomposition reaction and provide an equation
decomposition: AB = A + B
when one reactant is broken down into two or more simpler products
when bonds are broken is energy absorbed or released
absorbed
and therefore are decomposition reactions endothermic or exothermic
endothermic (bonds are broken therefore energy is absorbed to break substance bonds)
define pyrolysis
pyro - thermal, lysis (break down) therefore
pyrolysis = breaking down via heat, or THERMAL DECOMPOSITION
define electrolysis
electrolysis is ELECTRICAL DECOMPOSITION or where electric energy is used to break down (DECOMPOSE) compounds
define Photolysis
photolysis is where light energy is used to decompose compounds (LIGHT DECOMPOSITION)
define a combustion reaction
a combustion reaction is when reactants combine with oxygen to produce oxides while releasing heat energy
are combustion reactions endo or exo thermic
since bonds are broken, and then rearranged (formed) and heat energy is released, then combustion reactions are EXOTHERMIC
are combustion reactions oxidation or reduction reactions
oxidation reactions (fix explanation when understanding is confirmed) for now just remember combustion is OXIDATION
