Rates of reaction
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Rates of reaction

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    Rates of reaction Rates of reaction Presentation Transcript

    • Rates Of Reaction
      Flow Of Learning
    • Meaning Of Rate Of Reaction
      MEASUREMENT OF RATES OF REACTION:
      • Plot graph of quantity of product /
      reactant against time
      • Calculate the average rate of reaction
      • Calculate the rate of reaction at the specific time from the graph.
      EXPLANATION FOR THE RATE OF REACTION BASED ON COLLISION THEORY:
      • Particle Size
      • Concentration
      • Temperature
      • Catalyst
      -The meaning of Collision Theory.
      -To explain how each factor increases
      • Experiment On Effect Of Surface Area
      • Experiment On Effect Of Concentration
      • Experiment On Effect Of Temperature
      • Experiment On Effect Of Catalyst
      Is proven by
    • How KFC can cook Fried chicken in quickly?
    • Application of The Rate Of reaction In daily Activities
    • Observable changes in quantity that use to determine rate of reaction
      Meaning rate of reaction
      Unit for rate of reaction
      Avarage rate of reaction
      Measurement
      Rate Of Reaction
      Rate Of reaction at specific time
      Factors that affect rate of reaction
      Rate Of Reaction
    • Rate
      Speed = total Distance/Total time
      K.L
      J.B
    • Speed=
      Speed=
      =
      =
      = 100km/h
      = 300km/h
    • Reaction Types
      2
      1
      Chemical
      Bonds are made / broken
      Change in oxidation states
      Plasma
      Li
      +1
      P+1
      P+1
    • Chemical properties/ changes/ reactions (i.e., reactivity, combustibility).
      development of a gas, formation of precipitate, and change in color).
      Reactivity
      Combustibility
      Gas formation
      Precipitate
      Color change
    • Hydrogen-VERY reactive.
      Helium-Non-reactive.
    • The speeds of reactions are very varied
      • Rusting is a ‘slow’ reaction, you hardly see any change looking at it!
      • The weathering of rocks is an extremely very slow reaction.
      weathering of rocks
    • The fermentation of sugar to alcohol is quite slow but you can see the carbon dioxide bubbles forming in the 'froth' in a laboratory experiment or beer making in industry!
      Bubble gas
      • A faster reaction example is magnesium reacting with hydrochloric acid to form magnesium chloride and hydrogenor the even faster reaction between sodium and water to form sodium hydroxide.
      • Combustion reactions e.g. when a fuel burns in air or oxygen, is a very fast reaction.
    • Combustibility
      The tendency to react with Oxygen, releasing heat.
      O2
      BURNING
    • evidence of Chemical Change:
      development of a gas
      formation of precipitate
      change in color
    • Meaning Of Rate Of Reactions
      The rate of reaction is a measurement of the change in the quantity of reactant or product against time:
      Rate Of Reaction= Change in quantity of reactant / product
      Time taken
      Student ans: Changes of reactant or product against time (0 Mark)
    • Meaning Of Rate Of Reaction
      A rate of reaction is high if the reaction occurs fast within a short period of time..
      A rate of reaction is low if the reaction occurs slowly within a long period of time..
      A rate of reaction is inversely proportional to time:
      Rate of reaction α 1
      time taken
    • Meaning Of Rate Of Reactions
      The Higher rate of reaction the shorter time taken to complete the reaction
      The lower rate of reaction the longer time taken to complete reaction
      granule
      powder
      5 minute
      1 minute
      Which is the higher rate of reaction?
    • CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)
    • CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)
    • Observable changes
      The change in amount of reactant / product that can be measured :
      • Decrease in total quantity of mass / concentration of the reactant per unit of time.
      • Increase in total amount of mass / concentration of the product of reaction per unit of time
      • Total volume of the gas released.
      • Formation of precipitate.
    • Decrease in total quantity of mass / concentration of the reactant per unit of time.
    • Increase in total amount of mass / concentration of the product of reaction per unit of time
    • Total volume of the gas released.
      CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)
      Deliverytube
      Conical flask
      burette
      water
      Must shade!
    • Formation of precipitate.
      Na2SO3+2HCl->NaCl+S+SO2+H20
      PERCIPITATE
      stopwatch
    • Precipitatethe formation of insoluble ionic compounds.
      Does NOT dissolve in water.
    • Example:Study the reaction: Between calcium carbonate and excess 1 mol dm-3 hydrochloride acid.CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)
    • CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)
    • Observable changes
      CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)
      stopwatch
    • Observable changes
      CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)
      Hydrometer
    • Observable changes
      CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)
      Hydrometer
    • Observable changes
      CaCO3 (s) + 2HCl (aq) -> CaCl2(aq) + H2O + CO2 (g)
      Displacement Of water
    • Remember !!!
      CaCO3 (s) + 2HCl (aq) -> CaCl2 (aq) + H2O + CO2 (g)
      • Quantities of reactant will decreases against time
      • Quantities of product will increases against time
    • Measurement Rate Of Reaction
      Two ways to measure rate of reaction.
      Average Rate Of Reaction. :
      It is determined by calculating the total amount of reactant used or the total amount of product formed in a specific time.
      Rate Of Reaction at a specific time :
      It is determined by calculating the gradient of the graph at the time.
    • Introduction to the Rate of Reaction
      A reaction between small pieces of excess calcium carbonate with 80 cm3 hydrochloric acid 0.05M is conducted a laboratory to study the rate of reaction at interval time. The volume of gas released is recorded in the table below.
    • 40
      40
      30
      30
      27.00cm3
      37.00cm3
      Volume : 37-27=10 cm3
    • (a)
      Draw an apparatus to shows how this experiment
      can be conducted at laboratory.
      Must label the diagram!
    • x
      x




    • (b)
      Write a balance chemical equation for this reaction.
      CaCO3 (s) + 2HCl (aq) -> CaCl2(aq) + H2O + CO2 (g)
    • (c)
      CaCO3 + 2HCl -> CaCl2 + H2O + CO2
      CaCO3 + 2H++2Cl- -> Ca2++2Cl- + H2O + CO2
      CaCO3 + 2H++ -> Ca2++ H2O + CO2
      Remember !!!
      Only separate soluble salt
      Don’t separate covalentand insoluble salt
    • (d)
      Carbon dioxide gas
    • (e)
      A reaction between small pieces of excess calcium carbonate with 80 cm3hydrochloric acid 0.05M is conducted a laboratory to study the rate of reaction at interval time.
      Number of mole in the solution will use :
      MV
      Mol, n
      =
      1000
      0.05(80)
      =
      1000
      =
      0.004 mol
    • (f)
      CaCO3 + 2HCl -> CaCl2 + H2O + CO2
      From the chemical equation :
      Mole Ratios:
      2 mol HCl : 1 mol CO2
      0.004 mol HCl
      :
      0.004 mol HCl
      ×
      1 mol CO2
      2 mol HCl
      =
      0.002 mol CO2
      Volume of gas Co2 at room condition
      =
      0.002×24
      0.048 dm3
      =
    • (g)
      Because some of carbon dioxide gas can escape to surrounding during the experiment.
    • (h)
    • Volume of CO2, cm3
      Connect the point without using ruler!
      Not all the point is connected
      Time , s
    • Volume of CO2 cm3
      Cannot like this graph
      Straight line
      It’s must be smooth graph
      Time s
    • (i)
      Average Rate Of reaction
      The average rate of reaction in the first 90 seconds.
      = The total volume of gas released in the first 90 seconds
      Time taken
      33.5÷90=0.372 cm3s-1
      unit
      =
      Not cm3 per second
    • i(ii)
      The average rate of reaction in the whole experiment.
      = The total volume of gas released in the whole experiment
      Time taken
      47.5÷180= 0.264cm3s-1
      =
    • (h)
      Volume of gas against time
      y
      x
      α
      How to fit your scale in graph?
      For y: use ratio 5: 10
      Check it’s enough by 5÷10=0.5
      Maximum volume 47.5÷0.5=95 small boxes
      How about x:?
      30÷10=3
      Maximum 240÷3=80small boxes
    • Analysis of Data
      Rate of reaction at t second = gradient AB
      = p/q cm3 s-1
      Total volume of Hydrogen gas/cm3
      Tangent is a line that touch just 1 point of graph in order to calculate gradient
      B
      Tangent
      p
      A
      q
      Cannot take directly at x
      t
      Time (second)
    • Tangent
      Cannot touch more than 2 point because each of point have different gradient
      Only touch 1 point of curve
    • tangent
      α
    • Analysis of data
      Total Volume of CO2(cm3)
      F
      D
      E
      Rate of reaction at t1 = gradient AB
      B
      Rate of reaction at t2 = gradient CD
      C
      Rate of reaction at t3 = gradient EF
      Each of point have different gradient!
      A
      t1
      t3
      t2
      Time (second)
    • Two method to calculate tangent:
      Total volume of Hydrogen gas/cm3
      number of small boxes ×value of
      1 small unit box
      B
      Tangent
      Y
      A
      X
      Time (second)
    • First Method
      Gradient of graph:
      Total volume of Hydrogen gas/cm3
      m = ΔY
      ΔX
      B
      m = Y2-y1
      y2
      X2-x1
      Tangent
      A
      y1
      Time (second)
      x1
      x2
    • Analysis of Data
      Rate of reaction at t second = gradient AB
      = p/q cm3 s-1
      Total volume of Hydrogen gas/cm3
      B
      Tangent
      p
      A
      q
      t
      Time (second)
    • Analysis of data
      Total Volume of CO2(cm3)
      F
      D
      E
      Rate of reaction at t1 = gradient AB
      B
      Rate of reaction at t2 = gradient CD
      C
      Rate of reaction at t3 = gradient EF
      A
      t1
      t3
      t2
      Time (second)
    • From the answer of question (i) (iii) and (i) (iv),
      make a conclusion from the
      calculation of this experiment.
      (j)
      Ans : Rate of reaction will decreases
    • (k)
      Explain why does there is a difference of the rate
      of reaction at 30 second and 120 second.
      Ans: Rate of reaction at 30 second is higher because number of particles of reactant is higher than 120 second
    • (l)
      In your opinion, what will happen to the rate of reaction if,
      • The concentration of acid is increased.
      • A calcium carbonate powder is used in this
      experiment.
      • The volume of acid is increased.
      • The temperature of acid is increased.
      • A bigger conical flask is used.
      • The conical flask containing acid is shaken.