Please enable JavaScript.

Coggle requires JavaScript to display documents.

Unit 3 Learning Objectives: *1. Identify what conditions need to be met…

- - - - https://1drv.ms/u/s!AsMJlaYHHVrHgmXYXTwfg_SrlNHc?e=ec4348
        
        Reaction 3 has a higher rate of reaction than reaction 1 because not only does it have a low activation energy (maybe due to a catalyst) it also has a higher temperature. In other words the energy is much higher and many of the molecules will be able to react quickly
        
        Reaction 4 has a higher reaction rate than reaction 1. Both have a low temperature and a low activation energy but reaction 4 has a higher concentration, which gives the molecules more of a chance of collisions
        
        Reaction 1 has a higher reaction rate than reaction 2. Although both the reactions have low energy available to them, Reaction 1 has a much lower activation energy so more molecules are able to react successfully quicker.
- - - - This symbol stands for "extent of reaction". Instead of trying to count each collision, the rate of reaction is found by finding out finite larger changes.
        
        This is can also be expressed as a derivative
        
        The derivative or limit is used to find the reaction rate at a specific instance in time. The derivative of concentration in respect to time does this.
        RA = dcA/dt
      - Knowing this the rate of reaction can also be expressed as :
      - All the atoms are conserved in reactions and therefore there is a relationship between the rate of reaction of the reactants and the products.
        
        Rreactant 1 = Rreactant 2 = - Rproduct 1 = - Rproduct 2
        If the reaction is proceeding forwards:
        REACTANTS ARE ALWAYS NEGATIVE AND PRODUCTS ARE POSITIVE
        
        No atoms are lost, the products are negative because while the reactants are losing concentration the products are gaining in concentration
        
        NOTE: When calculating the rate of reaction the value is usually negative and that is why the negative sign in front of the rate of reaction of the products makes sense
        
        When a reaction has different stoichiometric coefficients the magnitudes of the rate of reactions will change and depending on whether they are reactants or products their signs will change
        
        Given the equation
        aA + bB ---> cC + dD
        
        Where the lowercases are stoichiometric coefficients and the uppercase are the molecules
        RA/a = RB/b = -RC/c = -RD/d
        
        The volumetric rate of reaction can be determined by just knowing values for one ractant
- - - - R = k[cA]^m[cB]^n
        
        where...
        k is the reaction rate constant with varying units
        m is the order of the first reaction. (The exponential change of concentration over time)
        n is the order of the second reactant. (")
        
        The value of k is dependent on the reaction in question. It can vary in the presence of a catalyst or at different temperatures.
        
        The reaction
        
        A catalyst
        
        Temperature change
        
        The order of the reaction (the exponents) indicates how the reaction changes in response to concentration changes for a specific reactant.
        
        commonly orders 0,1, and 2
        
        The overall reaction is m+n
        
        what happens to the reaction if.....
        
        m=0? This has no effect because anything to the power of 0 is 1 and anything multiplied by 1 is itself
        m=1 This doubles the concentration over that interval of time. This also doubles the rate of reaction.
        m=2 This quadruples the concentrations and therefore quadruples the reaction rate over that interval of time
        
        the stoichiometric coefficients do not have to do with the orders. unless they are elementary reactions elementary reactions have only one step and go directly from reactant to product. Many of the single step equations we see are really sequential steps written as an overall equation
        
        The speed of reaction is only as fast as it's slowest step. The slowest step is always the one with the highest activation energy.
        
        Method of Initial Rates
        
        This method finds the volumetric rate of the reaction from experimental data. Using the initial concentrations to calculate the order.
        
        These steps are taken:
        
        Write a rate law for each reaction
        
        Apply the rate law to two different reaction conditions and divide these expressions to determine the order of the reaction for a particular reactant.
        
        Repeat until all orders are known
        
        Obtain the reaction rate constant by substitution
  - - - The integrated rate laws for common orders:
        
        m = 0 cA(t) = -kt +cA0
        
        m = 1 lncA(t) = -kt +lncA0
        
        m = 2
    - - Found by substituting t1/2 wherever there is a "t" and making both sides equal 1/2cA0