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Equilibrium. I WISH I HAD SWEAT GLANDS. LeChatelier’s Principle. CO 2 + CaO CaCO 3. “chicken breath”. “food”. “egg shell”. As temperature increases , chickens “pant” more. This stresses the system and shifts the equilibrium to the. LEFT.
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Equilibrium I WISH I HAD SWEAT GLANDS. • LeChatelier’s Principle CO2 + CaO CaCO3 “chicken breath” “food” “egg shell” As temperature increases, chickens “pant” more. This stresses the system and shifts the equilibrium to the LEFT This makes the egg shells THIN and fragile.
I wish I had sweat glands. In summer, [ CO2 ] in a chicken’s blood due to panting. In a chicken… CaO + CO2 CaCO3 (eggshells) -- shift ; eggshells are thinner How could we increase eggshell thickness in summer? [ CO2 ] , shift -- give chickens carbonated water [ CaO ] , shift -- put CaO additives in chicken feed TOO much $$$ -- air condition the chicken house -- pump CO2 gas into the chicken house would kill all the chickens!
…favors the endothermic reaction (the reverse reaction) in which the rise in temperature is counteracted by the absorption of heat. Raising the temperature… …favors the forward reaction in which 4 mol of gas molecules is converted to 2 mol. Increasing the pressure… Decreasing the concentration of NH3… …favors the forward reaction in order to replace the NH3 that has been removed. LeChatelier’s Principle N2 + 3 H2 2 NH3 + heat Dorin, Demmin, Gabel, Chemistry The Study of Matter 3rd Edition, page 532
N2 + 3 H2 2 NH3 + heat Equilibrium Expression Haber Process Dorin, Demmin, Gabel, Chemistry The Study of Matter 3rd Edition, page 532
Animations • •Equilibrium Constant • •Calculating Keq • •Numerical Value of Keq
Reactant Product H2SO4 2 H1+ + SO42– Rate at which R P Rate at which P R = reversible reaction: Reactant Product and P R Acid dissociation is a reversible reaction. equilibrium: looks like nothing is happening, however… system is dynamic, NOT static
N2(g) + 3 H2(g) 2 NH3(g) Le Chatelier’s principle Le Chatelier’s principle: When a system at equilibrium is disturbed, it shifts to a new equilibrium that counteracts the disturbance. Disturbance Equilibrium Shift Add more N2………………….. “ “ H2………………….. “ “ NH3………………… Remove NH3………………….. Add a catalyst………………… no shift Increase pressure…………….
AgCl + energy Ago + Clo “energy” “energy” Light-Darkening Eyeglasses (clear)(dark) Go outside… Sunlight more intense than inside light; shift to a new equilibrium: GLASSES DARKEN Then go inside… shift to a new equilibrium: GLASSES LIGHTEN
Maintaining Blood pH Carbon dioxide is exhaled Acid entering the blood stream HCO31- + H+ H2CO3 H2O + CO2 Bicarbonate ion circulates in the blood stream where it is in equilibrium with H+ and OH-. In the lungs, bicarbonate ions combine with a hydrogen ion and lose a water molecule to form carbon dioxide, which is exhaled. Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 291
Alkalosis If our breathing becomes too fast (hyperventilation)… Carbon dioxide is removed from the blood too quickly. This accelerates the rate of degradation of carbonic acid into carbon dioxide and water. The lower level of carbonic acid encourages the combination of hydrogen ions and bicarbonate ions to make more carbonic acid. The final result is a fall in blood H1+ levels that raises blood pH which can result in over-excitability or death. Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 291
Acidosis If breathing becomes too slow (hypoventilation)… …free up acid, pH of blood drops, with associated health risks such as depression of the central nervous system or death. The normal pH of blood is between 7.2 – 7.4. This pH is maintained by the bicarbonate ion and other buffers. Kelter, Carr, Scott, Chemistry A World of Choices 1999, page 291