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Chemistry help needed... Confused?
The following reaction is first order and the rate constant is 2.35 x 10^-4 s^-1 at 20 degress C.
2 N2O5 -----> 2 N2O4 + O2
A.) What is the rate of reaction if the [N2O5]=.25 M?
B. What would the [N2O5] be after 100 s given that the initial [N2O5] was 0.25 M? What would be the [N2O4]
C. What is the half life for this reaction?
D. How long will it take for the initial [N2O5]=0.88M to drop to 0.11 M?
E) What is the activation energy for the reaction if the rate constant at 30 degrees C is 9.15 x 10^-4 s^-1
F.) What is the rate constant at 70 degrees C?
I'm confused on how to solve these and I have to show work. This is a sample problem for me to work on also all the C have to be changed by adding 273. If someone can show the work and how to get through this it would be very helpful! Thanks!
The following reaction is first order and the rate constant is 2.35 x 10^-4 s^-1 at 20 degress C.
2 N2O5 -----> 2 N2O4 + O2
A.) What is the rate of reaction if the [N2O5]=.25 M?
rate = k[N2O5]
B. What would the [N2O5] be after 100 s given that the initial [N2O5] was 0.25 M? What would be the [N2O4]
ln(Ao/A) = akt
C. What is the half life for this reaction?
k = 0.693/t1/2
D. How long will it take for the initial [N2O5]=0.88M to drop to 0.11 M?
ln(Ao/A) = akt
E) What is the activation energy for the reaction if the rate constant at 30 degrees C is 9.15 x 10^-4 s^-1
Use the Arrhenius equation.
F.) What is the rate constant at 70 degrees C?
Use the Arrhenius equation.
I can help you solve these chemistry problems step by step. Let's go through each question and explain how to find the answers.
A.) What is the rate of reaction if the [N2O5]=.25 M?
To find the rate of reaction, we need to use the rate equation for a first-order reaction, which is:
rate = k[N2O5]
where k is the rate constant and [N2O5] is the concentration of N2O5.
Given that the rate constant is 2.35 x 10^-4 s^-1, and [N2O5] = 0.25 M, we can substitute these values into the rate equation:
rate = (2.35 x 10^-4 s^-1)(0.25 M) = 5.875 x 10^-5 M/s
Therefore, the rate of reaction is 5.875 x 10^-5 M/s.
B. What would the [N2O5] be after 100 s given that the initial [N2O5] was 0.25 M? What would be the [N2O4]?
To find the [N2O5] after 100 s, we need to use the first-order reaction equation:
[N2O5]t = [N2O5]0 * e^(-kt)
where [N2O5]t is the concentration of N2O5 at time t, [N2O5]0 is the initial concentration of N2O5, k is the rate constant, and e is the base of the natural logarithm.
Given that the initial [N2O5] is 0.25 M, and the rate constant is 2.35 x 10^-4 s^-1, we can substitute these values into the equation:
[N2O5]100 = (0.25 M) * e^(-(2.35 x 10^-4 s^-1)(100 s))
Calculating this using a calculator, the [N2O5] after 100 s is approximately 0.153 M.
To calculate the [N2O4], we can use the stoichiometry of the reaction, which states that for every 1 mole of N2O5, 1 mole of N2O4 is formed. Since the initial [N2O5] was 0.25 M and it is a first-order reaction, the [N2O4] after 100 s would also be 0.153 M.
C. What is the half-life for this reaction?
The half-life of a first-order reaction can be calculated using the equation:
t(1/2) = ln(2) / k
where t(1/2) is the half-life, ln is the natural logarithm, and k is the rate constant.
Given that the rate constant is 2.35 x 10^-4 s^-1, we can substitute this value into the equation:
t(1/2) = ln(2) / (2.35 x 10^-4 s^-1)
Calculating this using a calculator, the half-life for this reaction is approximately 2951.67 seconds or 49.19 minutes (when considering the appropriate rounding).
D. How long will it take for the initial [N2O5]=0.88 M to drop to 0.11 M?
To find the time required for the initial [N2O5] to decrease to 0.11 M, we can rearrange the first-order reaction equation:
t = (1/k) * ln([N2O5]0 / [N2O5]t)
where t is the time, [N2O5]0 is the initial concentration of N2O5, [N2O5]t is the concentration of N2O5 at a given time, and k is the rate constant.
Substituting the given values ([N2O5]0 = 0.88 M, [N2O5]t = 0.11 M, k = 2.35 x 10^-4 s^-1) into the equation, we get:
t = (1 / (2.35 x 10^-4 s^-1)) * ln(0.88 M / 0.11 M)
Calculating this using a calculator, the time required for the initial [N2O5] to drop to 0.11 M is approximately 4711.49 seconds or 78.52 minutes.
E) What is the activation energy for the reaction if the rate constant at 30 degrees C is 9.15 x 10^-4 s^-1?
To calculate the activation energy for a reaction, we can use the Arrhenius equation:
k = A * e^(-Ea/RT)
where k is the rate constant, A is the pre-exponential factor or frequency factor, Ea is the activation energy, R is the gas constant (8.314 J/(mol K)), and T is the temperature in Kelvin.
Given that the rate constant at 30 degrees C (which is 273 + 30 = 303 K) is 9.15 x 10^-4 s^-1, we can plug these values into the Arrhenius equation:
9.15 x 10^-4 s^-1 = A * e^(-Ea / ((8.314 J/(mol K)) * (303 K)))
Since the pre-exponential factor (A) is not given, we cannot solve for the activation energy (Ea) without knowing it.
F.) What is the rate constant at 70 degrees C?
To find the rate constant at a different temperature, we can use the Arrhenius equation mentioned in the previous question:
k2 = k1 * e^(-Ea/R * ((1/T2) - (1/T1)))
where k1 is the rate constant at the initial temperature (30 degrees C or 303 K), k2 is the rate constant at the desired temperature (70 degrees C or 343 K), Ea is the activation energy, R is the gas constant (8.314 J/(mol K)), T1 is the initial temperature in Kelvin, and T2 is the desired temperature in Kelvin.
Given that k1 is 9.15 x 10^-4 s^-1, T1 is 303 K, T2 is 343 K, and we do not know the activation energy (Ea), we cannot calculate the rate constant (k2) without knowing the activation energy.
Please note that in some questions, you have mentioned changes to the units by adding 273. These conversions are required when dealing with temperature conversions from Celsius to Kelvin.
I hope this explanation helps you understand how to approach and solve these chemistry problems. If you have any further questions, feel free to ask!