Chemistry 2.2 by Holly Jones https://padlet.com/hol_cjones/o2gsbbjk02ja Made with a little mischief en-us 2019-01-30 12:12:16 UTC 2024-10-01 21:53:19 UTC hello@padlet.com Ppt reactions & rate 317683 https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795247 2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795247 Relationship between rate & [H2O2] 317683 https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795248 As the concentration of H2O2 increases, the rate also increase. It is directly proportional, first order process.]]> 2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795248 Colorimetry 317683 https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795250 We use colorimetry to track the rate of reaction where there is a colour change.

CH3COCH2 + I2 --> CH3COCH2I+ HI
Measure the intensity of the iodine - colorimeter. Rate of disappearance of iodine can be track/measured. ]]> 2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795250 Types of Catalyst hol_cjones https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795251 Homogeneous Catalysts
  • Reactants and catalyst are in the same state
  • Eg. A reaction in solution where the catalyst is a metal ion dissolved in water
Heterogeneous Catalysts
  • Reactants and catalysts are in different states
  • Eg. Reactions between gases that are catalysed on a solid metal surface
]]> 2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795251 Effect of temperatures hol_cjones https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795252
  • For a certain reaction, increasing the temperature by 10 degrees roughly doubles the number of particles with E>EA
    • Increasing Temperature
    • Make particles collide more frequently ( small increase in rate) 
    • Makes it more likely that collisions will cause a reaction  (more effective collisions) (large increase in rate) 
    ]]>     2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795252     Catalysis hol_cjones https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795253
  • A catalyst is a substance that speeds up a chemical reaction.
  • At the end of the reaction, the catalyst remains unchanged.
  • Catalysts increase reaction rates by providing alternative routes of lower activation energy.
    • ]]>     2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795253     Relationships between concentration and rate hol_cjones https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795254 When the concentration of reagant X doubles, there are a number of possible effects on this rate:
    Rate unchanged- rate not dependant on X
    Rate doubles - rate proportional to [X]
    Rate goes up by a factor of 4 - rate proportional to [X]2]]>     2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795254     Gas collection method 317683 https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795255 2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795255 Calculating rates II 317683 https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795256 Slope at t = Δ[products] ÷ Δt
    Rate at time, t = slope of tangent at t
    Units = moldm-3s-1]]>     2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795256     Calculating rates 317683 https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795257 To measure the rate, we need a physical or chemical quantity that varies with time.]]> 2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795257 Changes to increase RoR 317683 https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795258
  • Increasing temp. gives higher energies to particles & more effective collisions between them(& more often)
  • Increasing conc. of a reactant gives more particles & more collisions 
  • For gases, increasing pressure can restrict particles to a smaller volume to give more particles. The number of collisions will increase 
    • ]]>     2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795258     Collision theory 317683 https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795259 The more collisions between particles in a certain time, the faster the reaction.]]> 2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795259 Factors affecting rate of reaction 317683 https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795260
  • Surface area (of solid reactants)
  • Concentration (of reactants in solution)
  • Pressure (of gaseous reactants)
  • Temperature
  • Catalysis - adding a catalyst 
  • Light (in some cases)
    • ]]>     2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795260     Energy Profile hol_cjones https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795262 2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795262 Working out rates 317683 https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795263 1 ÷ t = rate (s-1)]]> 2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795263 Specified practical - Iodine-clock 317683 https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795264 Planning - decide on the volumes of H2O2 solution & water you mix together to get 4 different concentrations of H2O2. Each test requires:
    • 1cm3 starch solution 
    • 10cm3 H2SO4 solution
    • 10cm3 sodium thiosulpahte 
    • 25cm3 KI solution
    Total volume must be 50cm3. 
    General method -
    1. In separate conical flasks, make up solutions according to your concentration values(table) & the other chemicals. Don't add peroxide at this stage.
    2. Mix thoroughly
    3. Rapidly add the hydrogen peroxide to the test flask, starting the stop watch immediately after
    4. Swirl to mix the reaction mixture thoroughly
    5. Stop timing when the solutions turns blue-black & record the time
    6. Repeat the experiment for the other test flasks 



    ]]>     2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795264     Energy Distribution Curves hol_cjones https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795265
  • Shows us how energy is distributed amongst particles in a certain system
  • Shows our system as it is at a set temperature. 
  • The curve we see is called a Boltzmann Distribution
    • ]]>     2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795265     ACTIVATION ENERGY hol_cjones https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795266 Activation energy, EA , is the energy needed to start off a reaction]]> 2019-01-30 12:12:29 UTC https://padlet.com/hol_cjones/o2gsbbjk02ja/wish/325795266