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What do you need to know In order to write the equilibrium constant expression for a reaction?
To write the Keq for a reaction, the equilibrium concentrations of all reactants and products must be known. A specific example of this is how we define pH: the log of the equilibrium constant for any acid-base reaction. Just that simple, provided, of course, that the reaction does NOT go to 100% completion. Same principles apply to dissolution of partially soluble materials. If done correctly with consideration to chemical activity and coefficients, the so-called 'thermodynamic' equilibrium constants are obtained and are used in estimating quantities such as the entropy and enthalpy change of reaction.
The more difficult ( and interesting part ) is how do we know what those concentrations are? Mass balance equations are a good place to start along with any stoichiometric considerations...easy to stick to 1:1 electrolytes and other simple reactions.
What else can I help you with?
What are the units of the following if concentrations are expressed in mole per liter?
The units for the following equations would be: Rate of reaction: moles per liter per second Rate constant: per second Reaction order: unitless, but can be expressed as a number Equilibrium constant: unitless, as the units cancel out in the equilibrium expression
What is the rate law expression for a first-order reaction?
The rate law expression for a first-order reaction is: Rate kA, where Rate is the reaction rate, k is the rate constant, and A is the concentration of the reactant.
What is the relationship between the equilibrium constants Ka and Kb in a chemical reaction?
The equilibrium constants Ka and Kb are related by the equation Ka x Kb Kw, where Kw is the equilibrium constant for water. This relationship shows that as one equilibrium constant increases, the other decreases in order to maintain a constant value for Kw.
What is the order of a reaction if the graph is curve horizontal?
If the graph of a reaction's concentration versus time is a horizontal curve, it indicates that the concentration of the reactant is not changing over time, suggesting that the reaction has reached completion or is at equilibrium. This typically corresponds to a zero-order reaction, where the rate of reaction is constant and independent of the concentration of the reactants. In such cases, the rate remains constant until the reactants are depleted.
What is the rate constant for this zero-order reaction?
The rate constant for a zero-order reaction is a constant value that represents the rate at which the reaction proceeds, regardless of the concentration of reactants.
What is the rate constant for this first-order reaction?
The rate constant for a first-order reaction is a constant value that determines how quickly the reaction occurs. It is denoted by the symbol "k" and is specific to each reaction. The rate constant can be calculated by using experimental data from the reaction.
What happens when reactant is added to a system at equilibrium?
The equilibrium of the system will be upset.
How does an equilibrium reaction respond to the addiof extra reactant?
The concentration or activity of the product(s) will increase, and if there is at least one other reactant than the added one that is required for the completion of the reaction, the concentration of such an unadded reactant will decrease. (If there were no available unadded reactant, the reaction would not technically have been in equilibrium at the start, even though it may have reached a steady state that can persist for a long time in the absence of changed conditions.)
What is the rate constant for a zero-order reaction?
The rate constant for a zero-order reaction is a constant value that represents the rate at which the reaction proceeds, regardless of the concentration of reactants. It is typically denoted as "k" and has units of concentration/time.
How can one determine the rate constant for a second-order reaction?
To determine the rate constant for a second-order reaction, one can use the integrated rate law for a second-order reaction, which is: 1/At kt 1/A0. By plotting 1/At against time and finding the slope, which is equal to the rate constant k, one can determine the rate constant for the second-order reaction.
What is the effect of adding more water to the following equilibrium reaction?
Equilibrium is pushed to the reactant side
What is the value and unit of the rate constant for this reaction?
The value and unit of the rate constant for a reaction represent how fast the reaction occurs. The rate constant is typically denoted by the symbol "k" and its unit depends on the overall order of the reaction. The unit of the rate constant can be determined by the reaction rate equation.
