Equilibrium: Crash Course Chemistry #28

CrashCourse
26 Aug 201310:56
EducationalLearning
32 Likes 10 Comments

TLDRThe video discusses the concept of chemical equilibrium, which is when forward and reverse reactions happen at equal rates so there is no net change. It explores Le Châtelier's principle about how stresses like concentration changes, temperature, and pressure shifts equilibriums. As an example, it analyzes the Haber process for making ammonia, an equilibrium reaction industrially optimized by removing ammonia. Colorful demonstrations using cobalt ions shows equilibrium shifts from acid, base and temperature changes. Overall, it conveys equilibrium as a balanced state that seeks stability through adjustments from disturbances.

Takeaways
  • 😀 Chemical equilibrium is when forward and reverse reactions happen at the same rate, so there's no change in concentration over time.
  • 👨‍🔬 Le Châtelier's principle states that when stress is placed on a system at equilibrium, it will shift to minimize that stress.
  • 🔥 Increasing temperature, decreasing pressure, or adding reactants favors the endothermic direction.
  • ❄️ Decreasing temperature, increasing pressure, or removing products favors the exothermic direction.
  • 🧪 Concentration changes force a shift towards re-establishing the original concentrations.
  • ⚖️ Equilibrium seeks a balanced state, but is dynamic rather than static.
  • 🤯 Fritz Haber won the Nobel Prize for synthesizing ammonia from nitrogen and hydrogen.
  • 😢 Haber's process enabled explosives in WW1/WW2 though it later enabled fertilizer production.
  • 👍 Removing products from reactions can prevent equilibrium from being reached.
  • 🌈 Cobalt chloride equilibrium demonstration shows color change based on stress changes.
Q & A

  • What is chemical equilibrium?

    -Chemical equilibrium is when the rate of the forward and reverse reactions happen at the same rate, so there is no noticeable change in the concentration of reactants or products over time.

  • What is Le Châtelier's Principle?

    -Le Châtelier's Principle states that if stress is placed on a system at equilibrium, the system will proceed in a direction that minimizes the stress.

  • How can you disturb a chemical equilibrium?

    -A chemical equilibrium can be disturbed by changes in concentration, temperature, or pressure which shift the reaction towards the reactants or products.

  • What was Fritz Haber's contribution regarding ammonia production?

    -Fritz Haber invented an efficient industrial process to produce ammonia from nitrogen and hydrogen known as the Haber Process.

  • How does changing concentration affect equilibrium?

    -Increasing the concentration of reactants shifts the equilibrium towards the products. Decreasing the concentration of products shifts the equilibrium towards the reactants.

  • How does changing pressure affect equilibrium?

    -For gaseous reactions, increasing the pressure favors the side with fewer moles of gas. Decreasing the pressure favors the side with more moles of gas.

  • How does temperature affect equilibrium?

    -Raising temperature favors the endothermic reaction side. Lowering temperature favors the exothermic reaction side.

  • Why do most chemists try to prevent equilibrium?

    -Chemists try to maximize production of desired products by preventing the system from reaching equilibrium where forward and reverse reactions happen at equal rates.

  • Why was the Haber Process important?

    -The Haber Process enabled mass production of ammonia for fertilizers, supporting increased food production to feed a growing global population.

  • What colors were the cobalt ion solutions?

    -One cobalt ion solution was pink and the other was blue. Adding/removing reactants shifted the equilibrium and changed the color.

Outlines
00:00
🧘 Life Seeks Balance

The paragraph introduces the concept of balance in various aspects of life - financial, health, work-life - and how equilibrium is the scientific principle that regulates balance. It gives examples of how natural systems self-correct when equilibrium is disrupted, using a deer population and diet as analogies. The paragraph explains chemical equilibrium through reversible reactions, comparing it to maintaining balance on a moving board.

05:02
😵‍💫 Messing with Chemical Equilibrium

This paragraph explains Le Châtelier's Principle - when a chemical equilibrium is stressed, the system will react to minimize the stress. It gives the real-life example of the Haber process for making ammonia, describing how it reaches equilibrium and how equilibrium can be shifted to maximize production by changing conditions like temperature, pressure or concentration.

10:02
👩‍🔬 Applying Knowledge from History

The closing paragraph contrasts the failures and successes of Le Châtelier and Haber in developing the ammonia production process. It also summarizes key learnings - definition of chemical equilibrium, how it can be affected, Le Châtelier's observations - and credits the video creators.

Mindmap
Keywords
💡equilibrium
Equilibrium refers to a state of balance between opposing forces or reactions. In chemistry, it means the point where the rates of the forward and reverse reactions are equal, so there is no net change over time. The video explores how chemical equilibria can be disturbed by changes in concentration, temperature or pressure, but will eventually restore balance according to Le Châtelier's principle.
💡forward reaction
The forward reaction refers to the main reaction as written, where reactants form products. Understanding the concept of forward and reverse reactions is key because equilibrium happens when the forward and reverse reaction rates are balanced.
💡reverse reaction
The reverse reaction is the opposite of the forward reaction, where products break down into reactants. Equilibrium occurs when the forward and reverse reactions happen at equal rates, so there is no net change in concentrations over time.
💡stress
Stress refers to changes imposed on an equilibrium system, such as changes in concentration, temperature or pressure. According to Le Châtelier's principle, imposing stress causes a system at equilibrium to shift to counteract the stress and restore equilibrium.
💡Le Châtelier's principle
This important principle states that a system at chemical equilibrium will respond to disturbances by shifting in a direction that counteracts the disturbance and restores equilibrium. For example, adding reactants causes more products to be made to compensate.
💡endothermic
An endothermic reaction absorbs heat. According to Le Châtelier's principle, increasing temperature adds heat and thus favors the endothermic direction.
💡exothermic
An exothermic reaction releases heat. Lower temperatures favor exothermic reactions.
💡concentrations
Concentrations of reactants and products determine reaction rates. The video explains how changing concentrations disturbs an equilibrium, which then shifts to counteract the change.
💡pressure
For reactions involving gasses, pressure changes can disturb equilibrium and cause shifts. The video discusses how this works for the Haber process reaction.
💡temperature
Temperature changes affect equilibrium position, with heat favoring endothermic reactions and lower temperatures favoring exothermic ones.
Highlights

Chemical reactions seek balance like us and have to work through stress to find it

Many chemical reactions never fully stop, they reach equilibrium where forward and reverse reactions happen at equal rates

Reactions are reversible when they can go forward or backward without extra energy input

At equilibrium, no net change is observed in concentrations despite ongoing forward and reverse reactions

Le Châtelier's Principle: Systems at equilibrium will shift to minimize applied stress

Stresses like concentration changes make equilibrium shift towards restoring original balance

Increasing pressure stresses reactants more than products, favoring more product formation

Heat favors endothermic reactions, cooling favors exothermic ones

Most chemists make a living by preventing equilibrium to maximize desired products

Haber found efficient ammonia production method that eluded and traumatized Le Châtelier

Haber's process enabled fertilizers but he faced criticism for enabling chemical weapons

Equations and calculations can quantitatively predict equilibrium shifting

Cobalt equilibrium demonstration: acid and temperature shifts make color oscillate

Equilibrium isn't staying the same, it's keeping balance as circumstances change

Systems achieve equilibrium by compensating for changes rather than stopping reactions

Transcripts

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