Chemistry

The following table shows how the initial rate of this reaction depends on the concentrations of the two reactants

[NO] [O2] Initial rate
0.0050 0.0050 0.02
0.0050 0.0075 0.03
0.010 0.0075 0.12

Use the data to determine the order of reaction with respect to each of the reagents.

Sorry if the way I formatted the table looks really weird, thanks in advance!

  1. 👍 0
  2. 👎 0
  3. 👁 145
asked by Autumn
  1. In case the table is hard to read:
    [NO] / mol dm^-3
    Experiment 1: 0.0050
    Experiment 2: 0.0050
    Experiment 3: 0.010

    [O2] / mol dm^-3
    Experiment 1: 0.0050
    Experiment 2: 0.0075
    Experiment 3: 0.0075

    Initial Rate / mol dm^-3 s^-1
    Experiment 1: 0.02
    Experiment 2: 0.03
    Experiment 3: 0.12

    1. 👍 0
    2. 👎 0
    posted by Autumn
  2. rate 2 = k2(NO)^x(O2)^y is the equation for #2 and
    rate 1 = k1(NO)^x(O2)^y is the equation for #1 trial.
    I picked 2 and 1 because they have one reactant rate = to the same in another trial. Then divide first equation by second to get the final result of y = 1.

    Put in the numbers.and remember that k1 = k2 so we cancel them.
    0.03 (0.005)^x(0.0075)^y
    ------ = -----------------------------
    0.02 (0.005)^x(0.005)^y

    Note that (0.005)^x/0.005)^x cancels along with k1 and k2.
    1.5 = (1.5)^y so y must be 1;'i.e., the rxn is 1st order with respect to O2.
    Do the same kind of thing to find x.

    You will want to use #3 and #2 so that the (O2)^y/(O2)^y part cancels. Post your work if you get stuck.

    1. 👍 1
    2. 👎 0
    posted by DrBob222
  3. I got: 2nd order with respect to NO
    Thank you for the explanation!

    1. 👍 1
    2. 👎 0
    posted by Autumn
  4. So, are you saying that the answer is Rate=k[O2][NO]^2???????

    1. 👍 0
    2. 👎 0
  5. 2nd order with NO is right.
    Yes, x is 2, y is 1 so
    rate = k(NO)^2(O2)

    1. 👍 1
    2. 👎 0
    posted by DrBob222
  6. Orders of Rxn are 'rate trends' ... That is, look at the change in rate from initial concentration to 2x, 3x, etc. the initial concentration for each reactant. The general rule is hold all concentrations constant and vary one component at a time and note change in rates...
    If one changes concentration and change in rate = zero => 0 order reaction

    If one doubles concentration and change in rate doubles => 1st order reaction
    If one triples concentration and change in rate triples => 1st order reaction
    ( it’s a 1 to 1 linear trend)

    If one doubles concentration and change in rate increases 4x => 2nd order
    If one triples concentration and change in rate increases 9x => 2nd order
    ( it’s an exponential trend)

    For your problem
    Test………..[NO]…………. [O2]…….….. Initial rate
    …1………..0.0050………0.0050………….0.02
    …2………..0.0050………0.0075………….0.03
    …3………..0.0100………0.0075………….0.12

    Rxns 1&2 => holding [NO] constant, Δ[O₂] = 1.5x => ΔRate = 1.5 => 1:1 => 1st order in [O₂]
    Rxns 2&3 =>holding [O₂] constant, Δ[NO] = 2x => ΔRate = 4x => 1:4 => 2nd order in [NO]

    Rate = k[NO]²[O₂]¹ => k = Rate/[NO]²[O₂]¹
    Choose any row, k will be the same for all rows; i.e., constant.
    Row 1 => k = 0.02/(0.0050)²(0.0050) = 1.6 x 10⁵ L²∙sˉ¹∙molˉ²
    Row 2 => k = 0.03/(0.0050)²(0.0075) = 1.6 x 10⁵ L²∙sˉ¹∙molˉ²
    Row 3 => k = 0.12/(0.0100)²(0.0075) = 1.6 x 10⁵ L²∙sˉ¹∙molˉ²

    Numerical Rate Law => Rate = = 1.6 x 10⁵ L²∙sˉ¹∙molˉ²[NO]²[O₂]

    1. 👍 1
    2. 👎 0
    posted by Doc48

Respond to this Question

First Name

Your Response

Similar Questions

  1. Chemistry

    The reaction between NO (nitric oxide) and oxygen is a key step in the formation of acid rain. O2(g) + 2NO(g) → 2NO2(g) A series of experiments were run, each of which starts with a different set of reactant concentrations. From

    asked by Roman on March 27, 2012
  2. Chemistry

    The reaction X + Y --> products was studied using the method of initial rates. The initial rate of consumption of X was measured in three different experiments. What is the value of the rate constant, k? *concentrations are in

    asked by Jamie on February 23, 2011
  3. rate of reaction

    What is the initial rate of *appearance* of SO3(g)? a reaction and table are given: reaction: 2S02(g)+O2 -------> 2 SO3(g) Table note: i= initial, IRD= initial rate of disappearance; concentrations given in molarity (M) IRD given

    asked by j on July 20, 2011
  4. Chemistry

    Experiment 1: A has .20 M, B has .20 M and the initial rate is 2.0*10^-4M/min Experiment 2: A has .20 M, B has .40 M, and the initial rate is 8.0*10^-4M/min Experiment 3: A has .40 M, B has .40 M, and the initial rate is

    asked by Finn on August 20, 2015
  5. chemistry

    For the reaction H2(g) + I2(g) ¡ê 2 HI(g), you have the initial concentrations [H2] = 0.15 and [I2] = 0.05. Keq for the reaction at this temperature is 4.5 x 10-6. Make a reaction table. Include rows for initial concentration,

    asked by Anonymous on May 4, 2012
  6. chemistry

    For the reaction H2(g) + I2(g) ↔ 2 HI(g), you have the initial concentrations [H2] = 0.15 and [I2] = 0.05. Keq for the reaction at this temperature is 4.5 x 10-6. Make a reaction table. Include rows for initial concentration,

    asked by Anonymous on April 24, 2012
  7. chemistry

    For the reaction H2(g) + I2(g) ↔ 2 HI(g), you have the initial concentrations [H2] = 0.15 and [I2] = 0.05. Keq for the reaction at this temperature is 4.5 x 10-6. Make a reaction table. Include rows for initial concentration,

    asked by Anonymous on April 23, 2012
  8. chemistry

    The formation of nitroanalyine (an important intermediate in dyes, called ‘fast orange’) is formed from the reaction of ortho-nitrochlorobenzene (ONCB) and aqueous ammonia. (See Table 3-1 and Example 9-2.) The liquid-phase

    asked by john on February 24, 2011
  9. Chemistry

    For the reaction, 2 XO + O2 = 2 X02, some data obtained from measurement of the initial rate of reaction at varying concentrations are given below. run # [XO] [O2] rate, mol L-ls-l 1 0.010 0.010 2.5 2 0.010 0.020 5.0 3 0.030 0.020

    asked by Hannah on February 20, 2012
  10. Chemistry

    For the reaction, 2 XO + O2 = 2 X02, some data obtained from measurement of the initial rate of reaction at varying concentrations are given below. run # [XO] [O2] rate, mol L-ls-l 1 0.010 0.010 2.5 2 0.010 0.020 5.0 3 0.030 0.020

    asked by Hannah on February 20, 2012

More Similar Questions