I keep getting these questions wrong, could someone please help.
Thanks so much.
Question 1
For the following overall reaction, the rate constant is 3.4x10^-2.
A(g)+ 2B -> 2C + D
What may be the rate reaction?
Question 2
The rate law for this reaction is R=k[NO][Cl2]
Mechanism for the reaction.
NO + Cl2 -> NOCl2
NOCl2 + NO -> 2NOCl
Which of the following accurately describes this reaction?
2nd order reaction
The first step is the slow step
Doubling [NO] would quadrople the rate
Cutting [Cl2] in half would decrease the rate by a factor of 2.
The molecularity of the first step is 1.
Both steps are termolecular.
I'm not sure but for this particular question I think the answer may be 2nd order reaction and cutting [Cl2]....
For #2,
the reaction is 1st order with respect to NO and 1st order with respect to Cl2 which makes it 1+1 = 2 = 2nd order overall.
Cutting Cl2 in half is also true.
Doubling NO is not true.
The molecularity of the first step is not 1.
Both steps are termolecular is not true.
Thanks bro,
atleast I know the second question can be right.
calculate the ratio of rate constants for two thermal reactions that have the same arrhenius preexponential,but with activation energies that differ by 1,10, and 30 kJ/mol for T= 298K
For Question 1, the rate reaction can be determined by examining the stoichiometry of the overall reaction. Since 1 mole of A reacts with 2 moles of B, the rate expression can be written as follows:
Rate = k[A][B]^2
This means that the reaction is second order with respect to B.
For Question 2, the rate law given is R = k[NO][Cl2]. To determine the mechanism of the reaction, we need to analyze the individual steps and their molecularity.
The given mechanism is as follows:
Step 1: NO + Cl2 -> NOCl2 (Elementary reaction)
Step 2: NOCl2 + NO -> 2NOCl (Elementary reaction)
Now, let's analyze the options one by one:
1. 2nd order reaction - The overall reaction is not necessarily second order, so this option is not accurate.
2. The first step is the slow step - If the overall rate is determined by the slower step, then this option is correct. To determine this, we need to examine the rate-determining step, which is the slowest step in the mechanism. In this case, there is no information given about the rate constants of the individual steps, so we cannot determine the slow step from the given information.
3. Doubling [NO] would quadruple the rate - Since the rate law expression does not involve the concentration of NO raised to the power of 2, doubling the [NO] concentration would not quadruple the rate. Therefore, this option is incorrect.
4. Cutting [Cl2] in half would decrease the rate by a factor of 2 - Since the rate law expression involves the concentration of Cl2, cutting its concentration in half would indeed decrease the rate by a factor of 2. Therefore, this option is correct.
5. The molecularity of the first step is 1 - Molecularity refers to the number of reactant species involved in an elementary reaction. The first step involves the reaction between NO and Cl2, which is a bimolecular reaction (molecularity of 2). Therefore, this option is incorrect.
6. Both steps are termolecular - Termolecular reactions involve three reactant species colliding simultaneously, but none of the given steps are termolecular. Therefore, this option is incorrect.
Based on the analysis above, the correct answers for Question 2 are:
- Cutting [Cl2] in half would decrease the rate by a factor of 2.
- The molecularity of the first step is 2 (bimolecular).