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Kinetic Temperature Corrections

Environmental Engineering · FE Reference Handbook section

Environmental Engineering
18 formulas
10 exam-style examples
~60 min
All Environmental Engineering lectures

Handbook notes for this section

Definitions and conditions exactly as the handbook states them.

  • Monod growth rate constant as a function of limiting food concentration.

Core formulas for this FE topic

Definitions, applicability, units, assumptions and worked examples for each relation.

Worked exam-style examples

The four ways this section is written on the real exam — thoughts first, then equations, then substitution.

Example 1
Kinetic Temperature Corrections (Arrhenius theta) — solve for rate constant at T2 — Kinetic Temperature Corrections

kinetic temperature correction of a BOD rate constant using theta Given rate constant at T1 (k_T1) = 0.7000 1/day; temperature correction coefficient (theta) = 1.0910; temperature 2 (T2) = 31.0000 C; temperature 1 (T1) = 7.0000 C, determine the rate constant at T2 (k_T2) in 1/day.

Given

  • rate constant at T1 (k_T1) = 0.7000 1/day

  • temperaturecorrectioncoefficient(theta)=1.0910temperature correction coefficient (theta) = 1.0910
  • temperature2(T2)=31.0000Ctemperature 2 (T_{2}) = 31.0000 C
  • temperature1(T1)=7.0000Ctemperature 1 (T_{1}) = 7.0000 C

Find

rate constant at T2 (k_T2), in 1/day

Start with the thinking

  • The governing relation printed in this handbook section is Kinetic Temperature Corrections (Arrhenius theta).
  • Everything except k_T2 is given, so isolate k_T2 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Kinetic temperature corrections use the Arrhenius theta relationship to adjust reaction rate constants between two temperatures.

Step-by-step solution

  1. Step 1 — State the governing relation:

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}
  2. Step 2 — Rearrange symbolically for k_T2:

    kT2=kT1θ(T2−T1)k_{T2} = k_{T_1}\theta^{(T_2-T_1)}
  3. Step 3 — List the givens: rate constant at T1 (k_T1) = 0.7000 1/day, temperature correction coefficient (theta) = 1.0910, temperature 2 (T2) = 31.0000 C, temperature 1 (T1) = 7.0000 C.

  4. Step 4 — Substitute the given values:

    kT2=kT11.0910(T2−T1)k_{T2} = k_{T_1}1.0910^{(T_2-T_1)}
  5. Step 5 — Evaluate:

    kT2=5.6610 1/dayk_{T2} = 5.6610\ \text{1/day}
  6. Step 6 — Check: returning k_T2 = 5.6610 1/day to

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}

    reproduces the given quantities, and both sides carry the same units.

Answer:
kT2=5.6610 1/dayk_{T2} = 5.6610\ \text{1/day}

Why the other options are there

  • 11.3220 — kept a factor of two that cancels in the correct rearrangement.
  • 2.8305 — dropped that same factor in the other direction.
  • 6.2271 — rounded an intermediate value before the final step.

Reference: FE Handbook — Kinetic Temperature Corrections

Example 2
Kinetic Temperature Corrections (Arrhenius theta) — solve for rate constant at T1 — Kinetic Temperature Corrections (2)

Arrhenius-type temperature correction for a biological treatment rate constant Given temperature correction coefficient (theta) = 1.0530; temperature 2 (T2) = 13.5000 C; temperature 1 (T1) = 12.0000 C; rate constant at T2 (k_T2) = 4.3800 1/day, determine the rate constant at T1 (k_T1) in 1/day.

Given

  • temperaturecorrectioncoefficient(theta)=1.0530temperature correction coefficient (theta) = 1.0530
  • temperature2(T2)=13.5000Ctemperature 2 (T_{2}) = 13.5000 C
  • temperature1(T1)=12.0000Ctemperature 1 (T_{1}) = 12.0000 C
  • rate constant at T2 (k_T2) = 4.3800 1/day

Find

rate constant at T1 (k_T1), in 1/day

Start with the thinking

  • The governing relation printed in this handbook section is Kinetic Temperature Corrections (Arrhenius theta).
  • Everything except k_T1 is given, so isolate k_T1 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Kinetic temperature corrections use the Arrhenius theta relationship to adjust reaction rate constants between two temperatures.

Step-by-step solution

  1. Step 1 — State the governing relation:

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}
  2. Step 2 — Rearrange symbolically for k_T1:

    kT1=kT2θ(T2−T1)k_{T1} = \dfrac{k_{T_2}}{\theta^{(T_2-T_1)}}
  3. Step 3 — List the givens: temperature correction coefficient (theta) = 1.0530, temperature 2 (T2) = 13.5000 C, temperature 1 (T1) = 12.0000 C, rate constant at T2 (k_T2) = 4.3800 1/day.

  4. Step 4 — Substitute the given values:

    kT1=kT21.0530(T2−T1)k_{T1} = \dfrac{k_{T_2}}{1.0530^{(T_2-T_1)}}
  5. Step 5 — Evaluate:

    kT1=4.0535 1/dayk_{T1} = 4.0535\ \text{1/day}
  6. Step 6 — Check: returning k_T1 = 4.0535 1/day to

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}

    reproduces the given quantities, and both sides carry the same units.

Answer:
kT1=4.0535 1/dayk_{T1} = 4.0535\ \text{1/day}

Why the other options are there

  • 8.1070 — kept a factor of two that cancels in the correct rearrangement.
  • 2.0268 — dropped that same factor in the other direction.
  • 4.4589 — rounded an intermediate value before the final step.

Reference: FE Handbook — Kinetic Temperature Corrections

Example 3
Kinetic Temperature Corrections (Arrhenius theta) — solve for temperature correction coefficient — Kinetic Temperature Corrections (3)

temperature correction of reaction rate constant from summer to winter conditions Given rate constant at T1 (k_T1) = 1.6800 1/day; temperature 2 (T2) = 26.0000 C; temperature 1 (T1) = 20.0000 C; rate constant at T2 (k_T2) = 0.8270 1/day, determine the temperature correction coefficient (theta).

Given

  • rate constant at T1 (k_T1) = 1.6800 1/day

  • temperature2(T2)=26.0000Ctemperature 2 (T_{2}) = 26.0000 C
  • temperature1(T1)=20.0000Ctemperature 1 (T_{1}) = 20.0000 C
  • rate constant at T2 (k_T2) = 0.8270 1/day

Find

temperature correction coefficient (theta)

Start with the thinking

  • The governing relation printed in this handbook section is Kinetic Temperature Corrections (Arrhenius theta).
  • Everything except theta is given, so isolate theta symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Kinetic temperature corrections use the Arrhenius theta relationship to adjust reaction rate constants between two temperatures.

Step-by-step solution

  1. Step 1 — State the governing relation:

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}
  2. Step 2 — Rearrange symbolically for theta:

    θ=(kT2kT1)1/(T2−T1)\theta = \left(\dfrac{k_{T_2}}{k_{T_1}}\right)^{1/(T_2-T_1)}
  3. Step 3 — List the givens: rate constant at T1 (k_T1) = 1.6800 1/day, temperature 2 (T2) = 26.0000 C, temperature 1 (T1) = 20.0000 C, rate constant at T2 (k_T2) = 0.8270 1/day.

  4. Step 4 — Substitute the given values:

    θ=(kT2kT1)1/(T2−T1)\theta = \left(\dfrac{k_{T_2}}{k_{T_1}}\right)^{1/(T_2-T_1)}
  5. Step 5 — Evaluate:

    θ=0.8886\theta = 0.8886
  6. Step 6 — Check: returning theta = 0.8886 to

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}

    reproduces the given quantities, and both sides carry the same units.

Answer:
θ=0.8886\theta = 0.8886

Why the other options are there

  • 1.7772 — kept a factor of two that cancels in the correct rearrangement.
  • 0.4443 — dropped that same factor in the other direction.
  • 0.9774 — rounded an intermediate value before the final step.

Reference: FE Handbook — Kinetic Temperature Corrections

Example 4
Kinetic Temperature Corrections (Arrhenius theta) — solve for rate constant at T2 (case 2) — Kinetic Temperature Corrections (4)

kinetic temperature correction of a BOD rate constant using theta Given rate constant at T1 (k_T1) = 1.4900 1/day; temperature correction coefficient (theta) = 1.0970; temperature 2 (T2) = 27.5000 C; temperature 1 (T1) = 13.0000 C, determine the rate constant at T2 (k_T2) in 1/day.

Given

  • rate constant at T1 (k_T1) = 1.4900 1/day

  • temperaturecorrectioncoefficient(theta)=1.0970temperature correction coefficient (theta) = 1.0970
  • temperature2(T2)=27.5000Ctemperature 2 (T_{2}) = 27.5000 C
  • temperature1(T1)=13.0000Ctemperature 1 (T_{1}) = 13.0000 C

Find

rate constant at T2 (k_T2), in 1/day

Start with the thinking

  • The governing relation printed in this handbook section is Kinetic Temperature Corrections (Arrhenius theta).
  • Everything except k_T2 is given, so isolate k_T2 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Kinetic temperature corrections use the Arrhenius theta relationship to adjust reaction rate constants between two temperatures.

Step-by-step solution

  1. Step 1 — State the governing relation:

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}
  2. Step 2 — Rearrange symbolically for k_T2:

    kT2=kT1θ(T2−T1)k_{T2} = k_{T_1}\theta^{(T_2-T_1)}
  3. Step 3 — List the givens: rate constant at T1 (k_T1) = 1.4900 1/day, temperature correction coefficient (theta) = 1.0970, temperature 2 (T2) = 27.5000 C, temperature 1 (T1) = 13.0000 C.

  4. Step 4 — Substitute the given values:

    kT2=kT11.0970(T2−T1)k_{T2} = k_{T_1}1.0970^{(T_2-T_1)}
  5. Step 5 — Evaluate:

    kT2=5.7040 1/dayk_{T2} = 5.7040\ \text{1/day}
  6. Step 6 — Check: returning k_T2 = 5.7040 1/day to

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}

    reproduces the given quantities, and both sides carry the same units.

Answer:
kT2=5.7040 1/dayk_{T2} = 5.7040\ \text{1/day}

Why the other options are there

  • 11.4081 — kept a factor of two that cancels in the correct rearrangement.
  • 2.8520 — dropped that same factor in the other direction.
  • 6.2744 — rounded an intermediate value before the final step.

Reference: FE Handbook — Kinetic Temperature Corrections

Example 5
Kinetic Temperature Corrections (Arrhenius theta) — solve for rate constant at T1 (case 2) — Kinetic Temperature Corrections (5)

Arrhenius-type temperature correction for a biological treatment rate constant Given temperature correction coefficient (theta) = 1.1450; temperature 2 (T2) = 29.0000 C; temperature 1 (T1) = 13.0000 C; rate constant at T2 (k_T2) = 4.8710 1/day, determine the rate constant at T1 (k_T1) in 1/day.

Given

  • temperaturecorrectioncoefficient(theta)=1.1450temperature correction coefficient (theta) = 1.1450
  • temperature2(T2)=29.0000Ctemperature 2 (T_{2}) = 29.0000 C
  • temperature1(T1)=13.0000Ctemperature 1 (T_{1}) = 13.0000 C
  • rate constant at T2 (k_T2) = 4.8710 1/day

Find

rate constant at T1 (k_T1), in 1/day

Start with the thinking

  • The governing relation printed in this handbook section is Kinetic Temperature Corrections (Arrhenius theta).
  • Everything except k_T1 is given, so isolate k_T1 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Kinetic temperature corrections use the Arrhenius theta relationship to adjust reaction rate constants between two temperatures.

Step-by-step solution

  1. Step 1 — State the governing relation:

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}
  2. Step 2 — Rearrange symbolically for k_T1:

    kT1=kT2θ(T2−T1)k_{T1} = \dfrac{k_{T_2}}{\theta^{(T_2-T_1)}}
  3. Step 3 — List the givens: temperature correction coefficient (theta) = 1.1450, temperature 2 (T2) = 29.0000 C, temperature 1 (T1) = 13.0000 C, rate constant at T2 (k_T2) = 4.8710 1/day.

  4. Step 4 — Substitute the given values:

    kT1=kT21.1450(T2−T1)k_{T1} = \dfrac{k_{T_2}}{1.1450^{(T_2-T_1)}}
  5. Step 5 — Evaluate:

    kT1=0.5581 1/dayk_{T1} = 0.5581\ \text{1/day}
  6. Step 6 — Check: returning k_T1 = 0.5581 1/day to

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}

    reproduces the given quantities, and both sides carry the same units.

Answer:
kT1=0.5581 1/dayk_{T1} = 0.5581\ \text{1/day}

Why the other options are there

  • 1.1162 — kept a factor of two that cancels in the correct rearrangement.
  • 0.2791 — dropped that same factor in the other direction.
  • 0.6139 — rounded an intermediate value before the final step.

Reference: FE Handbook — Kinetic Temperature Corrections

Example 6
Kinetic Temperature Corrections (Arrhenius theta) — solve for temperature correction coefficient (case 2) — Kinetic Temperature Corrections (6)

temperature correction of reaction rate constant from summer to winter conditions Given rate constant at T1 (k_T1) = 1.9300 1/day; temperature 2 (T2) = 22.0000 C; temperature 1 (T1) = 29.5000 C; rate constant at T2 (k_T2) = 0.7010 1/day, determine the temperature correction coefficient (theta).

Given

  • rate constant at T1 (k_T1) = 1.9300 1/day

  • temperature2(T2)=22.0000Ctemperature 2 (T_{2}) = 22.0000 C
  • temperature1(T1)=29.5000Ctemperature 1 (T_{1}) = 29.5000 C
  • rate constant at T2 (k_T2) = 0.7010 1/day

Find

temperature correction coefficient (theta)

Start with the thinking

  • The governing relation printed in this handbook section is Kinetic Temperature Corrections (Arrhenius theta).
  • Everything except theta is given, so isolate theta symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Kinetic temperature corrections use the Arrhenius theta relationship to adjust reaction rate constants between two temperatures.

Step-by-step solution

  1. Step 1 — State the governing relation:

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}
  2. Step 2 — Rearrange symbolically for theta:

    θ=(kT2kT1)1/(T2−T1)\theta = \left(\dfrac{k_{T_2}}{k_{T_1}}\right)^{1/(T_2-T_1)}
  3. Step 3 — List the givens: rate constant at T1 (k_T1) = 1.9300 1/day, temperature 2 (T2) = 22.0000 C, temperature 1 (T1) = 29.5000 C, rate constant at T2 (k_T2) = 0.7010 1/day.

  4. Step 4 — Substitute the given values:

    θ=(kT2kT1)1/(T2−T1)\theta = \left(\dfrac{k_{T_2}}{k_{T_1}}\right)^{1/(T_2-T_1)}
  5. Step 5 — Evaluate:

    θ=1.1446\theta = 1.1446
  6. Step 6 — Check: returning theta = 1.1446 to

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}

    reproduces the given quantities, and both sides carry the same units.

Answer:
θ=1.1446\theta = 1.1446

Why the other options are there

  • 2.2892 — kept a factor of two that cancels in the correct rearrangement.
  • 0.5723 — dropped that same factor in the other direction.
  • 1.2590 — rounded an intermediate value before the final step.

Reference: FE Handbook — Kinetic Temperature Corrections

Example 7
Kinetic Temperature Corrections (Arrhenius theta) — solve for rate constant at T2 (case 3) — Kinetic Temperature Corrections (7)

kinetic temperature correction of a BOD rate constant using theta Given rate constant at T1 (k_T1) = 0.0900 1/day; temperature correction coefficient (theta) = 1.0720; temperature 2 (T2) = 27.0000 C; temperature 1 (T1) = 11.5000 C, determine the rate constant at T2 (k_T2) in 1/day.

Given

  • rate constant at T1 (k_T1) = 0.0900 1/day

  • temperaturecorrectioncoefficient(theta)=1.0720temperature correction coefficient (theta) = 1.0720
  • temperature2(T2)=27.0000Ctemperature 2 (T_{2}) = 27.0000 C
  • temperature1(T1)=11.5000Ctemperature 1 (T_{1}) = 11.5000 C

Find

rate constant at T2 (k_T2), in 1/day

Start with the thinking

  • The governing relation printed in this handbook section is Kinetic Temperature Corrections (Arrhenius theta).
  • Everything except k_T2 is given, so isolate k_T2 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Kinetic temperature corrections use the Arrhenius theta relationship to adjust reaction rate constants between two temperatures.

Step-by-step solution

  1. Step 1 — State the governing relation:

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}
  2. Step 2 — Rearrange symbolically for k_T2:

    kT2=kT1θ(T2−T1)k_{T2} = k_{T_1}\theta^{(T_2-T_1)}
  3. Step 3 — List the givens: rate constant at T1 (k_T1) = 0.0900 1/day, temperature correction coefficient (theta) = 1.0720, temperature 2 (T2) = 27.0000 C, temperature 1 (T1) = 11.5000 C.

  4. Step 4 — Substitute the given values:

    kT2=kT11.0720(T2−T1)k_{T2} = k_{T_1}1.0720^{(T_2-T_1)}
  5. Step 5 — Evaluate:

    kT2=0.2644 1/dayk_{T2} = 0.2644\ \text{1/day}
  6. Step 6 — Check: returning k_T2 = 0.2644 1/day to

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}

    reproduces the given quantities, and both sides carry the same units.

Answer:
kT2=0.2644 1/dayk_{T2} = 0.2644\ \text{1/day}

Why the other options are there

  • 0.5288 — kept a factor of two that cancels in the correct rearrangement.
  • 0.1322 — dropped that same factor in the other direction.
  • 0.2908 — rounded an intermediate value before the final step.

Reference: FE Handbook — Kinetic Temperature Corrections

Example 8
Kinetic Temperature Corrections (Arrhenius theta) — solve for rate constant at T1 (case 3) — Kinetic Temperature Corrections (8)

Arrhenius-type temperature correction for a biological treatment rate constant Given temperature correction coefficient (theta) = 1.0760; temperature 2 (T2) = 16.5000 C; temperature 1 (T1) = 13.5000 C; rate constant at T2 (k_T2) = 2.8380 1/day, determine the rate constant at T1 (k_T1) in 1/day.

Given

  • temperaturecorrectioncoefficient(theta)=1.0760temperature correction coefficient (theta) = 1.0760
  • temperature2(T2)=16.5000Ctemperature 2 (T_{2}) = 16.5000 C
  • temperature1(T1)=13.5000Ctemperature 1 (T_{1}) = 13.5000 C
  • rate constant at T2 (k_T2) = 2.8380 1/day

Find

rate constant at T1 (k_T1), in 1/day

Start with the thinking

  • The governing relation printed in this handbook section is Kinetic Temperature Corrections (Arrhenius theta).
  • Everything except k_T1 is given, so isolate k_T1 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Kinetic temperature corrections use the Arrhenius theta relationship to adjust reaction rate constants between two temperatures.

Step-by-step solution

  1. Step 1 — State the governing relation:

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}
  2. Step 2 — Rearrange symbolically for k_T1:

    kT1=kT2θ(T2−T1)k_{T1} = \dfrac{k_{T_2}}{\theta^{(T_2-T_1)}}
  3. Step 3 — List the givens: temperature correction coefficient (theta) = 1.0760, temperature 2 (T2) = 16.5000 C, temperature 1 (T1) = 13.5000 C, rate constant at T2 (k_T2) = 2.8380 1/day.

  4. Step 4 — Substitute the given values:

    kT1=kT21.0760(T2−T1)k_{T1} = \dfrac{k_{T_2}}{1.0760^{(T_2-T_1)}}
  5. Step 5 — Evaluate:

    kT1=2.2781 1/dayk_{T1} = 2.2781\ \text{1/day}
  6. Step 6 — Check: returning k_T1 = 2.2781 1/day to

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}

    reproduces the given quantities, and both sides carry the same units.

Answer:
kT1=2.2781 1/dayk_{T1} = 2.2781\ \text{1/day}

Why the other options are there

  • 4.5562 — kept a factor of two that cancels in the correct rearrangement.
  • 1.1391 — dropped that same factor in the other direction.
  • 2.5059 — rounded an intermediate value before the final step.

Reference: FE Handbook — Kinetic Temperature Corrections

Example 9
Kinetic Temperature Corrections (Arrhenius theta) — solve for temperature correction coefficient (case 3) — Kinetic Temperature Corrections (9)

temperature correction of reaction rate constant from summer to winter conditions Given rate constant at T1 (k_T1) = 1.6200 1/day; temperature 2 (T2) = 34.0000 C; temperature 1 (T1) = 5.5000 C; rate constant at T2 (k_T2) = 4.7870 1/day, determine the temperature correction coefficient (theta).

Given

  • rate constant at T1 (k_T1) = 1.6200 1/day

  • temperature2(T2)=34.0000Ctemperature 2 (T_{2}) = 34.0000 C
  • temperature1(T1)=5.5000Ctemperature 1 (T_{1}) = 5.5000 C
  • rate constant at T2 (k_T2) = 4.7870 1/day

Find

temperature correction coefficient (theta)

Start with the thinking

  • The governing relation printed in this handbook section is Kinetic Temperature Corrections (Arrhenius theta).
  • Everything except theta is given, so isolate theta symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Kinetic temperature corrections use the Arrhenius theta relationship to adjust reaction rate constants between two temperatures.

Step-by-step solution

  1. Step 1 — State the governing relation:

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}
  2. Step 2 — Rearrange symbolically for theta:

    θ=(kT2kT1)1/(T2−T1)\theta = \left(\dfrac{k_{T_2}}{k_{T_1}}\right)^{1/(T_2-T_1)}
  3. Step 3 — List the givens: rate constant at T1 (k_T1) = 1.6200 1/day, temperature 2 (T2) = 34.0000 C, temperature 1 (T1) = 5.5000 C, rate constant at T2 (k_T2) = 4.7870 1/day.

  4. Step 4 — Substitute the given values:

    θ=(kT2kT1)1/(T2−T1)\theta = \left(\dfrac{k_{T_2}}{k_{T_1}}\right)^{1/(T_2-T_1)}
  5. Step 5 — Evaluate:

    θ=1.0387\theta = 1.0387
  6. Step 6 — Check: returning theta = 1.0387 to

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}

    reproduces the given quantities, and both sides carry the same units.

Answer:
θ=1.0387\theta = 1.0387

Why the other options are there

  • 2.0775 — kept a factor of two that cancels in the correct rearrangement.
  • 0.5194 — dropped that same factor in the other direction.
  • 1.1426 — rounded an intermediate value before the final step.

Reference: FE Handbook — Kinetic Temperature Corrections

Example 10
Kinetic Temperature Corrections (Arrhenius theta) — solve for rate constant at T2 (case 4) — Kinetic Temperature Corrections (10)

kinetic temperature correction of a BOD rate constant using theta Given rate constant at T1 (k_T1) = 1.5900 1/day; temperature correction coefficient (theta) = 1.0680; temperature 2 (T2) = 6.5000 C; temperature 1 (T1) = 24.0000 C, determine the rate constant at T2 (k_T2) in 1/day.

Given

  • rate constant at T1 (k_T1) = 1.5900 1/day

  • temperaturecorrectioncoefficient(theta)=1.0680temperature correction coefficient (theta) = 1.0680
  • temperature2(T2)=6.5000Ctemperature 2 (T_{2}) = 6.5000 C
  • temperature1(T1)=24.0000Ctemperature 1 (T_{1}) = 24.0000 C

Find

rate constant at T2 (k_T2), in 1/day

Start with the thinking

  • The governing relation printed in this handbook section is Kinetic Temperature Corrections (Arrhenius theta).
  • Everything except k_T2 is given, so isolate k_T2 symbolically first — never rearrange after the numbers are in.
  • Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
  • Kinetic temperature corrections use the Arrhenius theta relationship to adjust reaction rate constants between two temperatures.

Step-by-step solution

  1. Step 1 — State the governing relation:

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}
  2. Step 2 — Rearrange symbolically for k_T2:

    kT2=kT1θ(T2−T1)k_{T2} = k_{T_1}\theta^{(T_2-T_1)}
  3. Step 3 — List the givens: rate constant at T1 (k_T1) = 1.5900 1/day, temperature correction coefficient (theta) = 1.0680, temperature 2 (T2) = 6.5000 C, temperature 1 (T1) = 24.0000 C.

  4. Step 4 — Substitute the given values:

    kT2=kT11.0680(T2−T1)k_{T2} = k_{T_1}1.0680^{(T_2-T_1)}
  5. Step 5 — Evaluate:

    kT2=0.5028 1/dayk_{T2} = 0.5028\ \text{1/day}
  6. Step 6 — Check: returning k_T2 = 0.5028 1/day to

    kT2=kT1θ(T2−T1)k_{T_2} = k_{T_1} \theta^{(T_2 - T_1)}

    reproduces the given quantities, and both sides carry the same units.

Answer:
kT2=0.5028 1/dayk_{T2} = 0.5028\ \text{1/day}

Why the other options are there

  • 1.0056 — kept a factor of two that cancels in the correct rearrangement.
  • 0.2514 — dropped that same factor in the other direction.
  • 0.5531 — rounded an intermediate value before the final step.

Reference: FE Handbook — Kinetic Temperature Corrections

© 2026 Dr. Steve Efe. Civil Engineering Capstone Studio. All rights reserved.