C6 - chemical reactions (changes, rate of reactions, redox)
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things needed for a reaction
particles need to collide with enough energy to start a reaction
ways to measure rate of reaction
-loss of mass -volume of gas produced
formula for average rate of reaction
-total mass lost/ time
why does rate of reaction decrease after 50%
-there are less reactant particles
define activation energy
The minimum energy colliding particles require to react
define successful collision
-collisions with enough energy to react
define limiting reactant
reactant that is used up first in a reaction
what affects rates of reactions
-temp -concentration -pressure of gas -Surface area of solids -catalysts
conclusion for temp.
-more kinetic energy -more movement -more frequent -more successful collision -faster rate of reaction
does concentration affect activation energy
no
how to increase concentration
-increase no. particles -decrease volume
conclusion for concentration/ pressure
-more concentration -more particles per unit volume -more frequent collisions -increased rate of reaction NO ENERGY CHANGE
relationship of Surface area & particle size
-more surface area -smaller particle size
conclusion of surface area
-smaller particle size -more surface area exposed to react -more frequent collisions -increased rate of reactions NO ENERGY CHANGE
define catalyst
-substance that speeds up the rate of a reaction but is unchanged at the end of the reaction
what does catalyst do to activation energy
-lower activation energy
conclusion of catalysts
-increase rate of reaction -by lowering activation energy -by providing an alternative reaction pathway -more successful collisions - greater proportion of particles with energy above the activation energy
more successful collisions or more frequent collisions
-temp = more frequent & successful collisions -concentration = more frequent collisions -surface area = more frequent collisions -catalyst = more successful collisions
how to find rate of reaction on graph
-make a tangent -draw lines extending from tangent - make a triangle -find gradient -ans can vary
define anomaly
result that doesn’t fit the pattern
how to write a conclusion
-describe results -explain - why
note: oxidation & reduction always go tgt
define spectator ion
-ion that doesn’t change in a reaction
diff. in numbering of oxidation state & ionic
oxidation state - +2 ionic - 2+