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natta225 [31]
3 years ago
13

For a particular first-order reaction, it takes 3.0 minutes for the concentration of the reactant to decrease to 25% of its init

ial value. what is the value for rate constant (in s-1) for the reaction?
Chemistry
1 answer:
grigory [225]3 years ago
5 0
We will use this formula for first order:
㏑[A] = - Kt +Ao
when we have t (given)= 30 min = 30 x 60 = 1800 s (we here convert time from min to second.
then we assume that the initial concentration Ao = 1
and the concentration of A (final concentration = 0.25 
So by substitution:
㏑(0.25) = - K * 1800 + ㏑(1)
1.39 = K * 1800 
∴ K = 0.00077 s^-1 or 7.7 x 10^-4
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What is the mass of 0.100 mole of neon? (Watch sf’s)
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Answer:

The answer to your question is letter D. 2.02 g

Explanation:

Data

moles of Ne = 0.100

atomic mass of Neon = 20.18 g

Process

1.- Use proportions to find the answer

                   20.18 g of Ne ------------------  1 mol of Ne

                        x                 ------------------  0.1 moles

                        x = (0.1 x 20.18)/1

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2.- Consider the significant figures

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4 0
3 years ago
Read 2 more answers
Which of the following processes have a ΔS < 0? Which of the following processes have a ΔS < 0? carbon dioxide(g) → carbon
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Answer:

All of the above processes have a ΔS < 0.

Explanation:

ΔS represents change in entropy of a system. Entropy refers to the degree of disorderliness of a system.

The question requests us to identify the process that has a negative change of entropy.

carbon dioxide(g) → carbon dioxide(s)

There is  a change in state from gas to solid. Solid particles are more ordered than gas particles so this is a negative change in entropy.

water freezes

There is  a change in state from liquid to solid. Solid particles are more ordered than liquid particles so this is a negative change in entropy.

propanol (g, at 555 K) → propanol (g, at 400 K)

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This reaction highlights a drop in temperature which means a negative change in entropy.

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6 0
3 years ago
The activation energy of a certain uncatalyzed biochemical reaction is 50.0 kJ/mol. In the presence of a catalyst at 37°C, the r
rodikova [14]

Answer:

E₁ ≅ 28.96 kJ/mol

Explanation:

Given that:

The activation energy of a certain uncatalyzed biochemical reaction is 50.0 kJ/mol,

Let the activation energy for a catalyzed biochemical reaction = E₁

E₁ = ??? (unknown)

Let the activation energy for an uncatalyzed biochemical reaction = E₂

E₂ = 50.0 kJ/mol

    = 50,000 J/mol

Temperature (T) = 37°C

= (37+273.15)K

= 310.15K

Rate constant (R) = 8.314 J/mol/k

Also, let the constant rate for the catalyzed biochemical reaction = K₁

let the constant rate for the uncatalyzed biochemical reaction = K₂

If the  rate constant for the reaction increases by a factor of 3.50 × 10³ as compared with the uncatalyzed reaction, That implies that:

K₁ = 3.50 × 10³

K₂ = 1

Now, to calculate the activation energy for the catalyzed reaction going by the following above parameter;

we can use the formula for Arrhenius equation;

K=Ae^{\frac{-E}{RT}}

If K_1=Ae^{\frac{-E_1}{RT}} -------equation 1     &

K_2=Ae^{\frac{-E_2}{RT}} -------equation 2

\frac{K_1}{K_2} = e^{\frac{-E_1-E_2}{RT}

E_1= E_2-RT*In(\frac{K_1}{K_2})

E_1= 50,000-8.314*310.15*In(\frac{3.50*10^3}{1})

E_1 = 28957.39292  J/mol

E₁ ≅ 28.96 kJ/mol

∴ the activation energy for a catalyzed biochemical reaction (E₁) = 28.96 kJ/mol

8 0
2 years ago
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