# Tag Info

## Hot answers tagged rate-equation

Accepted

### Deriving kinetic equations for reversible reactions

Actually you need concept of coupled differential equations but I suppose you can do a 'trick' to avoid it: $$\frac{dA}{dt} =- a A + b B$$ $$- \frac{dB}{dt} = - aA + bB$$ Are the form of the two ...

### Can anyone explain, why there are coefficients 2 in the equation for rate of change [A]?

$$\ce{A_n ->[k] nA}$$ For the reaction given above, rate of formation of $\ce{A}$ is defined as: $$\frac{1}{n}\frac{\mathrm d\ce{[A]}}{\mathrm dt} = k\ce{[A_n]}$$ In this case, we have three ...
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Accepted

### What is the rate law of a reaction: 2A + 3B → products?

If such a reaction "$\ce{2A + 3B -> }$ products" occurs, it is the sum of several more elementary reactions, which are taking place successively. Some may be fast, some slower. The rate ...
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Accepted

### Are the orders of reactants with respect to a reaction different for different starting concentrations?

A reaction's rate does depend upon the consumption of its reactants, and the manner in which the reactants interact. Let's consider the following reaction: $$\ce{A + B -> final products}$$ The rate ...
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### Why do alkenes (olefins) burn hotter than alkanes (paraffins), even though alkanes are denser and more hydrogen-rich?

Double-bonds are less stable, i.e., their formation is less exothermic, so it takes less energy to break one double bond than two singles. Or one triple vs. three single bonds. Consider triple-bonded ...
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### Deriving kinetic equations for reversible reactions

This is a classic example of the kinetics of reversible reactions. From the mechanism $\ce{A <=>[$k_\mathrm f$][$k_\mathrm b$] B}$ you can write the kinetic equations \begin{align} \frac{\...
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### How to calculate rate of carbon dioxide from rate equation?

Suppose we start with $n$ moles of $\ce{CO2}$ for simplicity. Then, at any point during the reaction, we will have $n-V_\text{gas}[\ce{CO2}]$ moles of each of the products. This means we could write ...
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### Calculate rate constant of second order reaction and pseudo first order reaction

The general rate law for a second order kinetics if $\pu{A_o < B_o}$, is $$\pu{\frac{1}{B_o - A_o} \ln\frac{A_o B}{A B_o} = kt}$$ If you only want to check that it is second oder, you can forget ...
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### pH for optimal kinetic for enzyme reaction

I don't think the rate equation is $v= \frac{k_2 [E]_0 [S]}{K_M(1+ [H+]/K_1 + K_2/[H+]) + [S]}$ I suspect it is rather: $$v= \frac{k_2 [E]_0 [S]}{(K_M + [S]) (1+ [\ce{H+}]/K_1 + K_2/[\ce{H+}])}$$ ...
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### Writing rate of disappearance and rate of appearance using rate law

You overthink it. It is just matter of eventual multiplication or division with respective stoichiometric coefficients. If there is an elementary reaction $$\ce{a A -> b B}$$ then for respective ...
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Using SymPy: ...
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### Can the RDS be different in different direction in a multi-step reversible reaction?

After discussion with OP in chat, the issue in logic can be rectified as follows. Simply put: $\ce{A<=>B<=>[slow]C <=> D}$ doesn't imply that $\ce{B <=> C}$ is the RDS in both ...
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