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3 years ago

A certain reaction has the following general form.

Chemistry

1 answer:

zhannawk [14.2K]3 years ago

6 0

Answer:

rate law = k [A]

Integrated rate law: ln [A] = -kt + ln[A]₀

m = -3.00 x 10⁻² Lmol⁻¹ s⁻¹

Explanation:

To determine the rate law we need to know the order of the reaction respect to the concentration of A.

In general, the rate law for a given equation is:

r= K [A ]^n

where rate , r , is the change in time of the concentration of A, and n is the order of the reaction.

So what we need to solve this question is find out which order of reaction conforms with the fact that a plot of 1/[A] versus time resulted in a straight line.

If zero order :

ΔA/Δt = - k [A]º = - k ⇒ ΔA = - k Δt

From calculus:

∫ [A] d[A] = -∫ kdt ⇒ [A] = -kt + [A]₀

A graph of this this equation will result in a straight line only graphing [A] versus time, and not 1/[A] vs time as stated in the question.

If first order.

r = - k[A] ⇒ ΔA/Δt = -k[A]

Δ[A]/[A] = - kΔt

A plot of 1/[A] vs t will result in a straight, so we now know the reaction is first order.

from calculus we know that this integrated gives us:

∫d[A]/[A] = -∫k dt

and the integral is:

ln [A] = -kt + ln[A]₀ where [A]₀ is the intial concentration of A.

you can see this equation has the form y = mx + b

So our reaction is first order, the integrated rate law is ln [A] = -kt + ln[A]₀ , and the values of the rate constant is the negative of the slope:

m= -k ⇒ k = - m = -3.00 x 10⁻² Lmol⁻¹ s⁻¹

In case you are wondering about the units for k : we are plotting 1/[A] vs time so it follows k will have the units of L/mol per s.

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2 years ago

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irina1246 [14]

Answer:

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Explanation:

Step 1: Write the unbalanced chemical equation,

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Step 2: Balance Carbon Atoms;

As there are 4 carbon atoms on left hand side and 1 carbon atoms on right hand site therefore, to balance them multiply CO₂ on right hand side by 4 i.e.

C₄H₁₀ + O₂ → 4 CO₂ + H₂O

Step 3: Balance Hydrogen Atoms;

There are 10 hydrogen atoms on left hand side and 2 hydrogen atom on right hand site therefore, to balance them multiply H₂O on left hand side by 5 i.e.

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C₄H₁₀ + 6.5 O₂ → 4 CO₂ + 5 H₂O

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2 C₄H₁₀ + 13 O₂ → 8 CO₂ + 10 H₂O

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2 years ago

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jasenka [17]

Answer:

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3 years ago

Which of the following is NOT a postulate of the Kinetic Molecular Theory?

kotegsom [21]

Answer:

"3. Energy can either be destroyed or created. Its goes from one form to another."

Explanation:

The third answer choice, "3. Energy can either be destroyed or created. Its goes from one form to another. " is related to the Law of Conservation of Energy from thermodynamics. Is it not a postulate of the Kinetic Molecular Theory.

"1. Average Kinetic Energy of the system is a measure of the temperature of the system."

Postulate of Kinetic Molecular Theory $\checkmark$

The average kinetic energy of the system is measured by its temperature and nothing else

"2. Energy is conserved in the collisions between gas molecules.."

Postulate of Kinetic Molecular Theory $\checkmark$

All collisions between gas molecules are perfectly elastic, meaning no energy is lost

"3. Energy can either be destroyed or created. Its goes from one form to another.

$\times$ NOT a Postulate of Kinetic Molecular Theory

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"4. Gases travel in straight line until they collide with other gas molecules"

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8 0

2 years ago

Find the initial concentration of the weak acid or base in each of the following aqueous solutions: (a) a solution of HClO with

Luda [366]

Answer:

a) 0.021 M

b) 0.019 M

Explanation:

To do this, you need to calculate the concentration of ions in solution with the given value of pH for each solution, then, write the chemical equation for both solutions, Set an ICE chart, use the value of Ka and Kb reported for both solutions, and solve for the initial concentration.

This is the general procedure to do it, now let's do it by parts.

a) Concentration of HClO pH = 4.6

With the given pH, we use the following expression:

pH = -log[H₃O⁺] From here, we solve for [H₃O⁺]

[H₃O⁺] = 10^(-pH) (1)

Let's calculate first the hydronium concentration:

[H₃O⁺] = 10^(-4.6) = 2.51x10⁻⁵ M

This value indicates the equilibrium concentration of this ion in solution. Now, to know the initial concentration of the acid, we need to do an ICE chart and write the chemical equation. This is an acid - base reaction, so we need the value of Ka of the acid.

HClO + H₂O <---------> H₃O⁺ + ClO⁻ Ka = 3x10⁻⁸

I: Y 0 0

C: -x +x +x

E: Y - x x x

With this chart, we need to write the expression for Ka which is:

Ka = [H₃O⁺] * [ClO⁻] / [HClO] = x² / Y-x

But we already know the concentration of [H₃O⁺], which is the same for [ClO⁻], and the value of Ka, so all we have to do is replace the values in the above expression and solve for Y:

3x10⁻⁸ = (2.51x10⁻⁵)² / Y - 2.51x10⁻⁵

We can round to Y because "x" is a very small value as it's value of Ka so:

3x10⁻⁸ = (2.51x10⁻⁵)²/Y

Y = (2.51x10⁻⁵)²/3x10⁻⁸

And this is the initial concentration of the acid.

b) Solution of hidrazine pH = 10.2

We do the same procedure as part a) with the difference that instead of using Ka , we use Kb and concentration of [OH⁻]. The Kb for hydrazine is 1.3x10⁻⁶

Let's calculate the [OH⁻]:

pOH = 14 - pH

pOH = 14 - 10.2 = 3.8

[OH⁻] = 10^(-3.8) = 1.58x10⁻⁴ M

The chemical equation:

N₂H₄ + H₂O <---------> N₂H₅⁺ + OH⁻ Kb = 1.3x10⁻⁶

I: Y 0 0

C: -x +x +x

E: Y-x x x

Kb = x²/(Y-x)

1.3x10⁻⁶ = (1.58x10⁻⁴)²/Y

Y = (1.58x10⁻⁴)²/1.3x10⁻⁶

And this is the initial concentration of hydrazine

4 0

2 years ago