Math Problem Statement

For cases where [A] exactly doubles:

• if the rate does not change, the order for A is 0. • if the rate doubles, then the order for A is 1. • if the rate quadruples, the order for A is 2.

For more complex cases, use the general equation:

What is the reaction order with respect to A? [A], mol/L [B], mol/L rate, mol/(L-min) Trial 1 0.771 0.682 0.0893 Trial 2 1.54 0.682 0.357 Trial 3 0.771 1.36 0.357 Trial 4 0.774 0.291 0.0164 Rate = k[A]orderA[B]orderB

Solution

The problem requires determining the reaction order with respect to [A][A] and [B][B] using the rate law:

[ \text{Rate} = k[A]^{\text{order}_A}[B]^{\text{order}_B} ]

We'll analyze the given data to find the reaction orders with respect to [A][A] and [B][B].

Step 1: Data Table Recap

Trial[A][A] (mol/L)[B][B] (mol/L)Rate (mol/(L·min))
10.7710.6820.0893
21.540.6820.357
30.7711.360.357
40.7740.2910.0164

Step 2: Determine Order of Reaction with Respect to [A][A]

To isolate the effect of [A][A], we compare trials where [B][B] remains constant. Comparing Trial 1 and Trial 2:

  • Trial 1: [A]1=0.771mol/L,Rate1=0.0893mol/(L\cdotpmin)[A]_1 = 0.771 \, \text{mol/L}, \, \text{Rate}_1 = 0.0893 \, \text{mol/(L·min)}
  • Trial 2: [A]2=1.54mol/L,Rate2=0.357mol/(L\cdotpmin)[A]_2 = 1.54 \, \text{mol/L}, \, \text{Rate}_2 = 0.357 \, \text{mol/(L·min)}
  • [B][B] remains constant at 0.682 mol/L.

Now, calculate the ratio of the rates and the concentrations:

[ \frac{\text{Rate}_2}{\text{Rate}_1} = \frac{k[A]_2^{\text{order}_A}[B]^{\text{order}_B}}{k[A]_1^{\text{order}_A}[B]^{\text{order}_B}} = \left(\frac{[A]_2}{[A]_1}\right)^{\text{order}_A} ]

0.3570.0893=(1.540.771)orderA\frac{0.357}{0.0893} = \left(\frac{1.54}{0.771}\right)^{\text{order}_A}

4=2orderA4 = 2^{\text{order}_A}

This gives us orderA=2\text{order}_A = 2.

Step 3: Determine Order of Reaction with Respect to [B][B]

Now, compare Trial 1 and Trial 3, where [A][A] remains constant:

  • Trial 1: [B]1=0.682mol/L,Rate1=0.0893mol/(L\cdotpmin)[B]_1 = 0.682 \, \text{mol/L}, \, \text{Rate}_1 = 0.0893 \, \text{mol/(L·min)}
  • Trial 3: [B]3=1.36mol/L,Rate3=0.357mol/(L\cdotpmin)[B]_3 = 1.36 \, \text{mol/L}, \, \text{Rate}_3 = 0.357 \, \text{mol/(L·min)}
  • [A][A] remains constant at 0.771 mol/L.

Again, calculate the ratio of the rates and concentrations:

[ \frac{\text{Rate}_3}{\text{Rate}_1} = \frac{k[A]^{\text{order}_A}[B]_3^{\text{order}_B}}{k[A]^{\text{order}_A}[B]_1^{\text{order}_B}} = \left(\frac{[B]_3}{[B]_1}\right)^{\text{order}_B} ]

0.3570.0893=(1.360.682)orderB\frac{0.357}{0.0893} = \left(\frac{1.36}{0.682}\right)^{\text{order}_B}

4=2orderB4 = 2^{\text{order}_B}

This gives us orderB=2\text{order}_B = 2.

Step 4: Conclusion

  • The reaction order with respect to [A][A] is 22.
  • The reaction order with respect to [B][B] is 22.
  • Therefore, the overall rate law is:

[ \text{Rate} = k[A]^2[B]^2 ]

Would you like more details on this or have any questions?

Here are 5 related questions you might find helpful:

  1. How do you calculate the rate constant kk given reaction data?
  2. What happens to the reaction rate if only [B][B] is doubled?
  3. How does temperature affect the rate constant kk?
  4. What is the difference between zero-order and first-order reactions?
  5. How would the rate law change if the reaction order with respect to AA was 1 instead of 2?

Tip: When determining reaction orders experimentally, always look for trials where only one reactant concentration changes while the others remain constant.

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Math Problem Analysis

Mathematical Concepts

Rate Law
Reaction Orders
Chemical Kinetics

Formulas

Rate = k[A]^orderA[B]^orderB
(Rate2 / Rate1) = ([A2] / [A1])^orderA
(Rate3 / Rate1) = ([B3] / [B1])^orderB

Theorems

Reaction Rate Theorem
Proportionality of Reaction Rate to Concentration

Suitable Grade Level

Grades 11-12 (High School Chemistry)