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3
votes
2answers
45 views

Why is the units of rate constant dependent on the order of the reaction?

In many textbooks, it is written that For order (m + n), the rate constant, k has units of mol1−(m+n)·L(m+n)−1·s−1 However, by the Arrhenius equation, k can be expressed as k = PZexp(-Ea/RT) and ...
0
votes
1answer
38 views

Question on notation

Here, when they write $v/(\mathrm{mol\ s^{-1}\ (kg\ \text{protein})^{-1}})$ is $0.30$ for the first row first column, do they mean that the value is $0.30\ \mathrm{mol\ s^{-1}\ (kg\ \text{protein})^{-...
3
votes
3answers
488 views

Can I express the rate of a reaction as percent per second (%/s)?

Rate is calculated as change in concentration over change in time, so usually $\pu{M/s}$ $(\pu{mol L-1 s-1}).$ Say, I'm calculating it for $20\%$ solution of ammonium hydroxide, so my final rate is ...
3
votes
1answer
93 views

How is the ln k term in the linearised Arrhenius equation acceptable?

In my syllabus we only study about rate laws under the topic "Rates of reactions", but as I was interested in it, I started to search about that topic. And then I found the Arrhenius equation $$\ln k ...
1
vote
1answer
203 views

Units of the rate constant for reactions whose order is greater than 1

In many textbooks, it is written that: The value of rate constant depends on the nature of the reactants, temperature and catalyst. It is independent of the concentration of the reactants. However,...
-1
votes
1answer
25 views

Rate constant converion [closed]

I need to calculate the half life for a first order reaction for which I need the rate constant $k$. From literature I observed that for a very closely simulated experiment I obtained the numerical ...
3
votes
1answer
152 views

Order of the reaction between hemoglobin and oxygen

I have the reaction: $$\ce{Hb + O2 <=>[$k$][$k'$] HbO2}$$ where $\ce{Hb}$ is hemoglobin, $k$ is the rate constant of the forward reaction, $k'$ is the rate constant of the inverse reaction. On ...
3
votes
0answers
39 views

Could the loss of mass in the kilogram be due to oxidation?

I was wondering about this. I have heard, and known for a while, that the famous and celebrated Prototype Kilogram - the lump of metal whose mass is used to define the standard mass scale worldwide - ...
1
vote
1answer
439 views

Reaction rate unit conversion: how to convert from molarity to ppm

How can I convert a reaction rate $k$ with units of $\mathrm{1\over M~~s}$ to $\mathrm{1\over ppm~~s}$? For context: I want to make a numerical simulation of a system of reactions that happens in air ...
1
vote
0answers
168 views

Rate constants using Arrhenius equation

If I'm trying to use the Arrhenius equation in this form: $$\ln\left(\frac{k_2}{k_1}\right) = -\frac{E_\mathrm a}R\cdot\left(\frac1{T_2}-\frac1{T_1}\right)$$ And I am given the activation energy ($...
9
votes
3answers
571 views

Units of rate constant (cycles per second vs radians per second) in Eyring equation

In the Eyring equation (EE), $$k = \frac{k_\mathrm B T}{h} \exp\left(\frac{-\Delta G_{\mathrm f}}{RT}\right),$$ the units of $k$ are $\mathrm{s^{-1}}$. However, in general rate constants are usually ...
-2
votes
1answer
883 views

Reaction rate constant conversion [closed]

I'm flustered, I'm not into chemistry and need to convert $\mathrm{(nM\cdot s)^{-1}}$ to $\mathrm{(M\cdot s)^{-1}}$. Is it correct to multiply with $10^9$?
7
votes
1answer
1k views

Units in modified Arrhenius equation?

The modified Arrhenius equation is used to express the rate constant in a chemical mechanism model I'm working with. The equations is as follows: $$k_\mathrm{f} = A\times T^b\times\exp\left(-\frac{E_\...
2
votes
1answer
899 views

Unit of time used in rate law equations

If doing a problem where you use the integrated rate law for a second order reaction ($\frac{1}{[\mathrm{A}]}-\frac{1}{[\mathrm{A_0}]}=kt$) to first find $k$, then use that to find the half-life. ...
3
votes
4answers
11k views

Why is the units of kcat 1/s?

I understand that $k_\text{cat}$ measures the turnover number of an enzyme. This measure is therefore a quantity of molecule conversions per unit of time. I suspect that my problem is more that of a ...
4
votes
1answer
1k views

How to find the units of the rate constant?

Consider the reaction $$\ce{2A + B -> Products},$$ when the concentration of $\ce{B}$ alone was doubled, the half-life did not change. When the concentration of $\ce{A}$ alone was doubled, the rate ...