Cave Chemistry

What cave formation needs:

1. Make a hole in the ground

2. Partially fill it with cool formations

Cave ChemistryCaCO3(s) Ca2+(aq) + CO3

2-(aq)

Ksp(CaCO3) = 4.8 x 10-9

Calculate solubility in mg/L:

Actual solubility: 80 mg/LWhy???

Effect of [CO2]. What should happen as [CO2] increases?

CaCO3(s) Ca2+(aq) + CO32-(aq)

CO2 + H2O H2CO3

H2CO3 HCO3- + H+ Ka1(H2CO3) = 4.2 x 10-7

HCO3- CO3

2- + H+ Ka2(HCO3-) = 4.8 x 10-11

CaCO3(s) Ca2+(aq) + CO32-(aq)

CO2(g) + H2O(l) H2CO3(aq)

H2CO3(aq) HCO3-(aq) + H+(aq) Ka1(H2CO3) = 4.2 x 10-7

HCO3-(aq) CO3

2-(aq) + H+(aq) Ka2(HCO3-) = 4.8 x 10-11

The Key Reaction is:

So: 1. Formation of the big hole

So: 2. Making those formations