Linked Questions

19
votes
2answers
1k views

Why does the reaction quotient use the products (multiplications) of reactants and products, rather than their respective sums?

As you may know, the reaction quotient $Q_c$ is defined by the equation $$ Q_c = \frac{[C]^\gamma [D]^\delta}{[A]^\alpha [B]^\beta} $$ for the chemical reaction $$ \alpha A + \beta B \rightarrow \...
16
votes
4answers
2k views

Relation between chemical kinetics and chemical equilibrium

In my chemistry book, the law of chemical equilibrium is derived from the law of mass action: For a reversible chemical reaction $$\ce{aA +bB\rightleftharpoons cC + dD}$$ where $a$, $b$, $c$ and $d$...
9
votes
2answers
2k views

Le Châtelier's Principle and heat

Consider the following reaction at equilibrium. $$\ce{A->B}, \Delta H < 0 $$ Suppose I increase the temperature. Now, quite a few people would invoke Le Châtelier's Principle and say that since ...
1
vote
4answers
6k views

How to find the empirical formula for an nitrogen oxygen compound from the given mass of nitrogen and the product?

$5.00~\mathrm{g}$ of nitrogen is completely converted into an oxide of nitrogen. The mass of the oxide formed is $19.3~\mathrm{g}$. The empirical formula of the oxide would be? My working: $$\ce{...
10
votes
1answer
795 views

When can I use concentrations instead of activities in equilibrium calculations?

To calculate an equilibrium constant, it is said that you should actually use activities $a_i$ instead of concentrations $c_i$. But it is also said that within a certain range, you can use ...
0
votes
2answers
642 views

Why is the rate of a reaction proportional to the concentrations of reactants raised to their stoichiometric coefficients?

Consider a gaseous state elementary reaction $$\ce{aA(g) + bB(g)} \overset{k_\mathrm{f}}{\underset{k_{\mathrm{b}}}{\ce{<=>}}}\ce{ cC(g) + dD(g)}$$ I know that for this reaction, $$\Delta G = \...
2
votes
0answers
2k views

Why does changing the dilution of an aqueous equilibrium shift the equilibrium?

Say we have the equilibrium $$\ce{A_{(aq)} + 2B_{(aq)} <=> C_{(aq)} + D_{(aq)}}$$ meaning the formula for the equilibrium constant is $$\ce{K_{c} = \frac{[C][D]}{[A][B]^2}}$$ My understanding is ...
2
votes
0answers
871 views

Why are the stoichiometric coefficients used as exponents in the chemical equilibrium constant?

From what I can ascertain, the formulation of the chemical equilibrium constant is somewhat arbitrary. I don't understand the motivation for putting the stoichiometric coefficients in the exponents. ...
-1
votes
1answer
45 views

Rate of a reaction [duplicate]

We know that the rate of a reaction $\ce{aA + bB -> cC + dD}$, the rate of the forward reaction is given by $r_\mathrm f = k_\mathrm f[\ce A]^p[\ce B]^q$ where $ a\neq p$ and $ b\neq q$ according ...
0
votes
0answers
41 views

Derivation of equilibrium constant [duplicate]

In general chemistry, we learn that the equilibrium constant, defined in terms of activities, for the reaction $$\ce{aA + bB -> cD + dD}$$ is given by $$K_\mathrm{eq} = \frac{(\ce{C})^c(\ce{D})^...