Chemical Equilibrium and the Acidification of the Ocean

A Chem 30 LessonJordan SevenhuysenFebruary 9th, 2012

Chemical EquilibriumJordan Sevenhuysen

The Problem:How does atmospheric CO2 levels effect

the pH of the ocean? What does this mean for marine organisms?

Carbon Cycle Learning Tool Ocean Acidification Grapher

H2O + CO2(aq)   H2CO3

HCO3–   H+ + CO3

2–

Ka2 = 4.7×10−11

CaCO3   Ca2+ + CO32–

Chemical EquilibriumJordan Sevenhuysen

H2CO3    H+ + HCO3–

Ka1 = 2.5×10−4  

P(CO2) = kH[CO2(aq)]

CO2 and Ocean pH Applet

H2O + CO2(aq)   H2CO3

Kh = 1.70×10−3

HCO3–   H+ + CO3

2–

Ka2 = 4.7×10−11

CaCO3   Ca2+ + CO32–

Ksp = 3.7×10−9 to 8.7×10−9

Chemical EquilibriumJordan Sevenhuysen

H2CO3    H+ + HCO3–

Ka1 = 2.5×10−4  

P(CO2) = kH[CO2(aq)]kH = 29.76 atm/(mol/L)

Concepts Developed/Used:• Equilibrium systems• Le Chatelier’s Principle• ICE tables• Acid/Bases• Ka, Kb

Main goal is to have students work with and explore equilibrium expressions and equations.

Chemical EquilibriumJordan Sevenhuysen

POS ObjectivesUnit D: Chemical Equilibrium Focusing on Acid-Base Systems

• Students will explain that there is a balance of opposing reactions in chemical equilibrium systems. (General Outcome 1)

• Students will identify, write and interpret chemical equations for systems at equilibrium. (30-D1.2k)

• Predict, qualitatively, using Le Chatelier’s principle, shifts in equilibrium caused by changes in temperature, pressure, volume, concentration or the addition of a catalyst and describe how these changes affect the equilibrium constant. (30-D1.3k)

Chemical EquilibriumJordan Sevenhuysen