How do I determine the units of the rate constant for a zero order, first order, second order, and third order reaction?

Md Ariful Islam

0 like 0 dislike
1 views
Share with your friends

1 Answers

Md Ariful Islam

Call

You will need to be able to write a general and solve for the units...

$r(t) = k[A]^n$

$r(t)$ is the initial rate as a function of time $t$, $k$ is the rate constant, $[A]$ is the concentration of $A$, and $n$ is the order of $A$.

Since $A$ is assumed the only reactant for simplicity, its order IS the reaction order. If the units of time are $"s"$, and of concentration are $"M"$, then:

$"M"/"s" = [???] cdot "M"^n$

$=> [???]$

$=$ $color(blue)("units of rate constant in general")$

$= color(blue)("M"^(1 - n)/"s")$

So,

  • zero order should simply be $"M"^(1 - 0)/"s" = "M/s"$.
  • first order should be $"M"^(1 - 1)/"s" = 1/"s"$.

Can you work out second order and third order?

0 like 0 dislike
1 views
Talk Doctor Online in Bissoy App
If the reaction is first order in $A$ and second order in $B$, what is the rate constant if $[A] = "0.40 M"$ and $[B] = "0.14 M"$?

Well, I can't figure out what all your numbers are, but I can give you a general idea of what to do. You know that the reaction is first order...

1 Answers 1 views
A first order reaction has an Arrhenius constant for the reaction is $9.9 xx 10^10 sec^ -1$, and an activation energy of $"62.0 kJ"$. At what temperature (in Celsius) is the rate constant equal to $0.434 sec^-1$?

Your tool of choice here will be the Arrhenius equation, which looks like this $color(blue)(|bar(ul(color(white)(a/a)k = A * "exp"(-E_a/(RT))color(white)(a/a)|)))" "$, where $k$ - the rate constant for a...

1 Answers 1 views
A second-order reaction has a rate constant of 0.007500/(M · s) at 30°C. At 40°C, the rate constant is 0.05800/(M · s). The activation energy is 161.23 kJ/mol. What is the frequency factor, A?

This is a pretty straightforward Arrhenius equation practice problem, so make sure that you're familiar with the Arrhenius equation,which looks like this $color(blue)(|bar(ul(color(white)(a/a)k = A * "exp"(-E_a/(RT))color(white)(a/a)|)))" "$,...

1 Answers 1 views
The rate constant of a first order reaction is $4.60 xx 10^(-4) "s"^(-1)$ at $350^@ "C"$. If the activation energy is $"104 kJ/mol"$, what is the temperature at which the rate constant is $8.80 xx 10^(-4) "s"^(-1)$?

I get $371^@ "C"$. Let's look at what we have: $k_1 = 4.60xx10^(-4) "s"^(-1)$ at $T_1 = 350^@ "C"$, the rate constant for the reaction at temperature $1$...

1 Answers 1 views
The rate constant of the reaction $O(g) + Na_2(g) -> NO(g) + N(g)$, occurring in the stratosphere, is $9.7 x 10^10 L mol^-1s^-1$ at 800 C. The activation energy of the reaction is 315 kJ/mol. How do you determine the rate constant at 700 C?

The Arrhenius Equation gives: $sf(k=Ae^(-E_a/(RT)))$ $sf(k)$ is the rate constant $sf(A)$ is the frequency factor, which is constant for a particular reaction $sf(R)$ is the gas constant, $sf(8.31"J/K/mol")$ $sf(T)$ is...

1 Answers 1 views
$2A(g) + B(g) -> C(g)$. Rate = $k[A]^2[B]$. At the beginning of one trial of this reaction, [A] = 4.0 M and [B] = 1.0 M. The observed rate was 0.048 $"mol"*"L"^(-1)*"s"^(-1)$. What is the value of the rate constant for this reaction closest to?

The is $"rate" = k["A"]^2["B"]$ ∴ $k = "rate"/(["A"]^2["B"]) = (0.048 color(red)(cancel(color(black)("mol·L"^"-1")))"s"^"-1")/(("4.0 mol·L"^"-1")^2 × 1.0 color(red)(cancel(color(black)("mol·L"^"-1")))) = "0.0030 L"^2"mol"^"-2""s"^"-1"$

1 Answers 1 views
Consider the following reaction: 2 NO(g) + 2 H2(g) → N2(g) + 2 H2O(g) Use the data below to find the rate law and determine the value of the rate constant? Make sure to report proper units!

This question is concerned with the method of initial rates which can be used if more than one species is reacting. In this case, as the reaction proceeds the concentration...

1 Answers 1 views
The reaction rate law is known to be 2nd order, and for an initial concentration [NO2(g)]o=0.0100M, the initial rate is 0.0350 M/s. Write the rate law, and give the value of the rate constant?

$"2NO"_2 → "2NO" + "O"_2$ If the reaction is second order and $"NO"_2$ is the only reactant, the rate law is $"rate" = k["NO"_2]^2$ $k = "rate"/(["NO"_2]^2) = ("0.0350 mol·L"^"-1""s"^"-1")/("0.0100...

1 Answers 1 views
The rate law of a reaction is rate = k[D][X]. What are the units of the rate constant?

The rate constant $k$ takes on whatever units it needs to such that the units on the lefthand side are the same as on the righthand side. Supposing the units...

1 Answers 1 views
What organisms are the producers, first order consumers, second order consumers, and third order consumers in an ecosystem?

This is all a part of the food chain! Think of a tree, which is a producer. The tree produces acorns that a number of organisms can feed on, such...

1 Answers 1 views
X