Rates of Reaction :: GCSE Chemistry Coursework Investigation

Rates of replyWhat is a ramble of response?The amount of change of a crop or reactant in a given time.What affects the localize?a) Concentration of resolving (more likely to collide as more in same vol.)b) Temperature (increases f number of groinecules, more exceed EA)c) Surface bea (same as ingress)d) Pressure of gas pedalses (same as conc.)e) Catalyst (guide particles to correct predilection + lowers EA)f) Others e.g. light(light = increase in speed of particles)How are rates altered?Collision theoryParticles must collide with an cypher exceeding the EA and they musthave the correct orientation.A reception rate increased by,- Increasing collision frequency- Increasing average kinetic energy of particles- Lowering activation energy- Giving molecules correct orientationEffect of concentration on raterA = rate of reaction with respect to AE.g. RH+ = rate of reaction with respect to H+(aq)Rate of reaction = K Aa Bb CcUnits of rates of reaction = mol dm-3 s-1Units of con centration = mol dm-3Indices a, b, c etc order of reaction - what is the effect on therate of doubling the concentrationE.g. H+1 = 1st order = if conc. is doubled, rate is doubledH+2 = second order = if con. is double, rate is quadrupledH+0 = zero order = if conc. is doubled, rate is unaffectedThe constant, KK = rate constant. This is a constant of proportionalityUnits may modify but must include s-1rA = kA1B1mol dm-3 s-1 = k (mol dm-3)(mol dm-3)for mol dm-3 s-1 to = mol dm-3 s-1because k must = dm3 mol-1 s-1because (mol dm-3)(mol dm-3) = mol2 dm-6, so to equal this out,k = dm3 mol-1 s-1Expt. 11.2a the kinetics of the reaction between calcium carbonate andhydrochloric acidCaCO3(s) + 2HCl(aq) CaCl2(aq) + CO2(g) + H2O(l)Collect gas given off in a syringe.Create a boardTime (s)Volume of CO2 Vt (cm3)(Vfinal - Vt) cm3Then to find the order, find the one-half - life if time periods areroughly the same between for each one half - life then it is first order. Ifit is second order the g raphical record would increase and not be constant.Methods of following a reactionBy titrationE.g. reaction between iodine and propane in acid solution.Then on a graph time can be plotted against titre values, in this casea straight line is seen, suggesting the reaction to be zero orderBy colorimetryCan be use when one of the reactants or products have a colour, the impregnation changing during the reaction. The intensity can be followedusing a special colorimeter.By DilatometryWhere during the reaction the total volume of the solution changes.