Unit 2.2 - rate of reaction Flashcards
what is rate?
change in concentration over time
what is it measured in?
moldm-3s-1
what is the collision theory?
for a reaction between 2 molecules to occur an effective collision must take place (product must be formed)
particles need activation energy
Reaction rate?
a measure of the frequency of effective collisions
what are the factors affecting the rate of reaction?
concentration, temp,particle size, catalyst and light
concentration?
rate increases as concentration increase
more particles, hence more collisions
temperature?
increasing the temp, increases Kinetic energy, causing an increase in successful collisions
particle size?
reducing particle size, increasing surface area and increases the number of collisions per unit time
catalyst?
increases the rate of chemical reaction without undergoing a permanent change itself
provides an alternate route with a lower activation energy
light?
uv light provides energy for free radical substitute
Activation energy?
minimum energy required for a reaction to proceed by breaking bonds
Boltzman distribution curve?
at higher temperatures, a greater fraction of the molecules have energy above activation energy
homogenous catalyst?
same physical state as the reactants. It takes an active part in the reaction and is not a spectator ion
2 examples of homogenous catalyst?
concentrated H2SO4 in the formation of an ester from a carboxylic acid + alcohol
Fe2+ions in the oxidation of iodide ions by sodium triosulphate (Na2S2O3)
heterogenous catalyst?
in a different physical state to the reactants
Iron in the haber process - to make amounts
vanadium 5 oxide - used in the contact process to make H2So4
Nickel in the hydrogenation of margerine
