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BARSIC [14]
3 years ago
13

If a temperature increase from 21.0 ∘c to 35.0 ∘c triples the rate constant for a reaction, what is the value of the activation

barrier for the reaction?
Chemistry
1 answer:
Airida [17]3 years ago
4 0

Answer:

59.077 kJ/mol.

Explanation:

  • From Arrhenius law: <em>K = Ae(-Ea/RT)</em>

where, K is the rate constant of the reaction.

A is the Arrhenius factor.

Ea is the activation energy.

R is the general gas constant.

T is the temperature.

  • At different temperatures:

<em>ln(k₂/k₁) = Ea/R [(T₂-T₁)/(T₁T₂)]</em>

k₂ = 3k₁ , Ea = ??? J/mol, R = 8.314 J/mol.K, T₁ = 294.0 K, T₂ = 308.0 K.

ln(3k₁/k₁) = (Ea / 8.314 J/mol.K) [(308.0 K - 294.0 K) / (294.0 K x 308.0 K)]

∴ ln(3) = 1.859 x 10⁻⁵ Ea

∴ Ea = ln(3) / (1.859 x 10⁻⁵) = 59.077 kJ/mol.

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zzz [600]

Answer:

A. Strong initial heating caused some of the hydrate sample to spatter out of the crucible.

Explanation:

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The percentage of water in the sample is lower than expected.

A. Strong initial heating caused some of the hydrate sample to spatter out of the crucible:

If part of the sample is splashed from the crucible the mass of water detected will be less.

B. The dehydrated sample absorbed moisture after heating:

If the sample absorbs water after heating the percentage of water would be higher than expected.

C. The amount of the hydrate sample used was too small:

Depending on the sample size, different procedures can be chosen for analysis.

D. The crucible was not heated to constant mass before use:

In many occasions the crucible is heated next to the sample and not in previous form.

E. Excess heating caused the dehydration sample to decompose:

If the sample decomposes during heating, the analysis should be discarded.

success with your homework

4 0
3 years ago
What is the element above the element in Group 3, Period 4?
Dennis_Churaev [7]
Scandium? Is that what you mean?
5 0
3 years ago
How does the adaptations of a giraffe help survive its environment
strojnjashka [21]

Answer:

"They drink water when it is aivailable but can go weeks without it, they rely on morning dew and the water content of their food". they can use plants as resources to live.

7 0
2 years ago
Which distinguishes chemical changes from physical changes?
7nadin3 [17]

Answer:

In a chemical reaction, there is a change in the composition of the substances; in a physical change there is a difference in the appearance, smell, or simple display of a sample of matter without a change in composition.

Explanation:

7 0
3 years ago
When 60 mL of 0.22 M NH4Cl is added to 60 mL of 0.22 M NH3, relative to the pH of the 0.10 M NH3 solution the pH of the resultin
densk [106]

Answer:

Will be more acidic

Explanation:

The equilibrium of NH3 in water is:

NH3(aq) + H2O(l) ⇄ NH4⁺(aq) + OH⁻(aq).

Where equilibrium constant, Kb, is:

Kb = 1.85x10⁻⁵ = [NH4⁺] [OH⁻] / [NH3]

From 0.10M NH3, the reaction will produce X of NH4⁺ and X of OH⁻ and Kb will be:

1.85x10⁻⁵ = [X] [X] / [0.10M]

1.8x10⁻⁶ = X²

X = 1.34x10⁻³ = [OH⁻]

As pOH = -log[OH⁻] = 2.87

And as pH = 14 - pOH

pH of the 0.10M NH3 is 11.13

Now, to find the pH of the NH4Cl and NH3 we need to use H-H equation for bases:

pOH = pKb + log [NH4⁺] / [NH3]

<em>Where pKb is -log Kb = 4.74 and [] are moles of both compounds.</em>

<em />

Moles of [NH4⁺] = [NH3] = 60mL, 0.060L*0.22M = 0.0132moles:

pOH = 4.74 + log [0.0132] / [0.0132]

pOH = 4.74

pH = 14 - 4.74 = 9.26

That means the pH of the resulting solution will be more acidic

7 0
3 years ago
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