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Wize University Chemistry Textbook > Equilibrium

Intro to Equilibrium + characteristics of dynamic equilibrium

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Introduction to Equilibrium

Some chemical systems react to completion.

Example:
Ti+(aq) + Cl-(aq) → TiCl(s)


But other reactions form an equilibrium. These reactions are reversible and go in both directions.

Example:
ClNO2(g)+NO(g) ⇌ NO2(g)+ClNO(g)

Equilibrium is when the rate of the forward reaction=the rate of the reverse reaction
  • Is this stationary or dynamic?
    dynamic
  • There is no net change


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Understanding Equilibrium

In the bottle below, CO2 gas is leaving the dissolved state and entering the gas state
CO2(aq) → CO2(g)

At the same time, CO2 gas state is leaving the gas state and entering the liquid state
CO2(g) → CO2(aq)


Since both the forward and backward reactions are occurring at the same time, we write:
CO2(g) ⇌ CO2(aq)

  • There are no visible changes while this is happening
  • There are no (macroscopic/microscopic)
    macroscopic
    changes, but there are (macroscopic/microscopic)
    microscopic
    changes

Extra Practice
The digestion of some high-protein foods such as red meat, beans, lentils, and shell-fish, releases uric acid, HC5H3N4O3(aq), which ionizes into hydrogen ions, H+(aq) and urate ions, C5H3N4O3-(aq) in the bloodstream. People whose kidneys do not function properly cannot excrete urate ion sufficiently quickly, leading to an increased concentration of urate in the blood. This sometimes leads to a painful form of arthritis known as gout, characterized by the formation of tiny needle-like crystals of sodium urate, NaC5H3N4O3(aq), in joints and tissues according to the equation:
NaC5H3N4O3(s) ⇌ Na+(aq) + C5H3N4O3-(aq)
a) Suppose you are a nutritionist. What advice could you give to your patients who suffer from gout? Explain why the advice would be effective [2]
Equilibrium
Choose which statement completes the following sentence to make it false. Once a dynamic equilibrium is reached ----------------
Choose which statement completes the following sentence to make it false.
Once a dynamic equilibrium is reached ___________
Equilibrium
Choose which statement completes the following sentence to make it false. Once a dynamic equilibrium is reached ----------------
Dynamic equilibria
A new experiment, for which the balanced chemical equation is unknown, was performed in the lab.
aA(aq)+bB(aq)⇄dD(aq)aA(aq)+bB(aq)\rightleftarrows dD(aq)
The concentrations of the different species (A, B and D) were monitored and plotted as a function of time, as shown below. Which of the following statements concerning this reaction is true?
Indicate the CORRECT statement regarding concentrations at equilibrium:
The graph below shows the rate of the forward (top curve) and reverse (bottom curve) over time
Which of the following statements are CORRECT
i. After point B the forward and reverse rates are equal because [products]=[reactants]
Indicate the CORRECT statement regarding concentrations at equilibrium:
Chemical Equilibria
Consider this balanced chemical reaction and the molecular representation for both of the next two questions: 2AB(g)⇌A2(g)+B2(g)2AB(g)⇌A_2(g)+B_2(g)