General Chemistry
Improve your experience by picking them
Consider the following first-order reaction:
2 N2O5(g) → 2 N2O4(g) + O2(g)
If the reaction has an activation energy of 103 kJ/mol and an Arrhenius constant of 2.01×1013 s–1, calculate the rate constant of the reaction at 650 K.
Among the two reactions below, predict which will have a smaller orientation factor and justify your answer.
Reaction A. SO3(g) + H2O(g) → H2SO4(g)
Reaction B. H(g) + Br(g) → HBr(g)
Calculate the activation energy (in kJ/mol) of a reaction if the rate of the reaction increases by a factor of 3.5 when the temperature is increased from 40°C to 60°C. If the temperature is increased raised from 110°C to 130°C, by how much will the rate of the reaction increase?
At 40°C, the rate constant of a particular first-order reaction is 2.6×10–4 s–1. Calculate the activation energy in kJ/mol if the rate of the reaction quadruples when the temperature is increased to 70°C.
The activation energy (Ea) is 160 kJ/mol and the frequency factor (A) is 4.73×1010 /(M•s) for the bimolecular reaction below:
H2(g) + I2(g) → 2 HI(g)
What is the rate constant of the reaction at 300°C?
An ester hydrolysis reaction takes 6.80 h to complete at 45.0 °C but takes 2.25 h to complete when the temperature is raised to 85.0 °C. Calculate the activation energy (in kJ/mol) for the reaction.
An esterification reaction has an activation barrier of 19.5 kJ/mol at 25.0 °C. The activation barrier is lowered to 12.3 kJ/mol when a catalyst is added to the reaction mixture. If the frequency factor for the reaction does not change, how many times faster is the catalyzed reaction than the uncatalyzed reaction?
Starch can be hydrolyzed into glucose in the presence of the amylase enzyme. The reaction takes place under very mild conditions in the presence of the enzyme (In a neutral solution at 25.0 °C) with a rate constant of 3.25×103 s–1. In the absence of the enzyme, the reaction takes place very slowly and under harsh reaction conditions (In a highly acidic solution at 80.0 °C) with a rate constant of 7.84×10–2 s–1. If the uncatalyzed reaction was carried out at 25.0 °C instead of 80.0 °C, would it take place faster or slower?
Using the energy profile given below, identify whether the forward or the reverse reaction is faster. (kf > kr or kf < kr)
The following graph is an Arrhenius plot for two different chemical reactions (marked Reaction 1 and Reaction 2). Determine which one of the two reactions has a smaller value of the pre-exponential factor (A).
The following graph is an Arrhenius plot for two different chemical reactions (marked Reaction 1 and Reaction 2). Identify which one of the two reactions has a smaller value of the activation energy (Ea).
Ethanol can be dehydrated over alumina (Al2O3) catalyst to yield ethylene (C2H4) and water.C2H5OH(g) → C2H4(g) + H2O(g)The activation energy and the frequency factor for the reaction are 26.6 kJ/mol and 3.00×108 s–1, respectively. Calculate the rate constant for the reaction at 75.0 °C. Assume that the activation energy and the frequency factor do not change with temperature.
A catalyst increases a chemical reaction's rate by lowering its activation energy. A particular chemical reaction has an activation energy of 125 kJ/mol at 45 °C. The activation energy is lowered by 55 kJ/mol when a catalyst is added to the reaction. Calculate the factor by which the rate of the reaction is increased. Assume that the frequency factor remains the same.
The rate of a chemical reaction increases as the temperature is increased. The following table shows how the value of the rate constant (k) changes as the temperature is increased.Using the data in the table, calculate the value of Ea and A.
Hydrogen peroxide decomposes quickly into water and oxygen gas in the presence of a platinum catalyst. The decomposition reaction takes place in two steps:Step 1: Pt + H2O2 → H2O + Pt(O) (slow)Step 2: Pt(O) + H2O2 → Pt + O2 + H2O (fast)Will the rate of the reaction change if oxygen is removed from the reaction mixture?
Isomerization of n-butane to isobutane is a bit difficult to accomplish because it requires breaking C-C bonds. The activation barrier for the transformation is 120 kJ/mol. What fraction of n-butane molecules with an energy equal to or greater than the activation barrier exists at 455 K and 575 K. Also determine the ratio of the two fractions (at 575 K to 455 K).
Calculate the fraction of xenon (Xe) atoms having an energy of 6.40 kJ/mol or greater at a temperature of 150 °C?
The rate constant for the first-order decomposition of hydrogen peroxide into water and oxygen is 7.652×10−12 s−1 at 313 K and 2.516×10−10 s−1 at 343 K. What is the value of the frequency factor for this reaction?
The rate constant values for a hypothetical reaction are 1.356×10−3 s−1 and 2.412×10−3 s−1 at 35.0 °C and 43.0 °C, respectively. Calculate the value of the rate constant at 52.0 °C.
The rate constant values for a hypothetical reaction are 1.250×10−4 s−1 and 8.764×10−3 s−1 at 345 K and 360 K, respectively. Calculate the value of activation energy.
Consider the following gas-phase reactions:1. 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g)2. H2(g) + Cl2(g) → 2 HCl(g)The two reactions are carried out under identical temperature and pressure conditions. If we assume that the activation energy for reactions is the same, which one will still proceed faster?
The table below shows the results of a kinetics study for the alkaline hydrolysis of ethyl acetate.CH3COOC2H5 + NaOH → CH3COONa + C2H5OH
The reaction is second-order overall (First order in ethyl acetate and first-order in sodium hydroxide). Calculate the value of the rate constant at 10.0 °C.
The following table shows various values of the rate constant (k) obtained at different temperatures. Use this data to construct an Arrhenius plot and calculate the value of the frequency factor (A) and the activation energy (Ea).
A reaction was carried out in replicates. Each replicate reaction was carried out at a different temperature while keeping the rest of the conditions identical. Multiple values of k were obtained at different temperatures. A plot of lnk vs 1/T (in Kelvin units) has a downward slope with a value of −6453 K. What is the activation energy for the reaction?
The activation energy for a hypothetical first-order reaction is 134 kJ/mol.A → ProductsThe frequency factor for the reaction is 2.53×1012 s−1 at 500 K. Calculate what fraction of A converts into products in 1 minute at this temperature
The activation energy for the hydrolysis of urea under atmospheric conditions is 60.93 kJ/mol. However, the urease enzyme boosts the reaction rate by a factor of 13.6 million. Calculate the difference in activation energy between the catalyzed and uncatalyzed reactions. Assume that the frequency factor for both reactions is the same at 25.0 °C.
Calculate the rate constant for a reaction that has an activation energy of 45.8 kJ/mol and a frequency factor of 2.38×1010 /s at 38.0 °C.
The rate constant of a reaction was determined to be 2.39 × 10–3 s–1 at 350 K and 1.08×10–2 s–1 at 400 K. Determine the rate constant of the reaction at 385 K.
For the reaction CH4(s) + 2 O2(g) → CO2(g) + 2 H2O(g), the rate constants were determined to be
2.3 M–1 s–1 at 650 K14.5 M–1 s–1 at 900 K
Calculate the rate constant at 800 K.
In a certain experiment, the rate constant of a reaction was determined in different temperatures. The table below shows the temperature (T) and rate constant (k) collected during the experiment. Plot ln k vs 1/T and determine the activation energy (Ea, in kJ/mol)) and pre-exponential factor (A, in s–1) of the reaction.
In the graph shown below, each line correspond to a different reaction. Arrange the reactions in order of decreasing activation energy.
In an experiment, the temperature dependence of the rate constant was determined. Using the data below, calculate the pre-exponential factor, A.
In an experiment, the activation energy of a reaction was found to be 131 kJ/mol. A catalysis was used to increase the rate of the reaction by a factor of 107. Calculate the difference in the activation energy of the uncatalyzed vs. catalyzed reactions. Assume that the pre-exponential and temperature of both reactions are identical.
The activation energy of an uncatalyzed reaction is 95 kJ/mol. The addition of a catalyst lowers the activation energy to 55 kJ/mol. Assuming that the collision factor remains the same, by what factor will the catalyst increase the rate of the reaction at (a) 25°C
A reaction has a rate constant of 0.0117/s at 400.0 K and 0.689/s at 450.0 K. Determine the activation barrier for the reaction.
The rate constant (k) for a reaction was measured as a function of temperature. A plot of ln k versus 1/T (in K) is linear and has a slope of −8193 K. Calculate the activation energy for the reaction.