Question

Calculate the concentration of CO2 in water (in mmol/L) at
15 and 20°C (ΔHdissolCO2 = -5,242 cal/mol, R = 1.987 cal/Kmol)

Answer 1

Apply the relation

H = n_g RT

- 5242 ₌ n_g x 1.987 x 288

n_g  = -5242 / 288 x 1.987

..... = - 9.1602 mol / L

,,,,,or = - 9160.2 mmol /L

Note The negative value indicates that the number of CO2 (g) moles get reduced on sissolution of CO2 in water & has to be ignored .Thus the concentration of CO2 in water is = 9160.2 mmol / L

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similarly concentration of CO2 in water at 20^o C-

n_g = -5242 / 293 x 1.987

........= - 9.0039 mols / L

...or, = - 9.0039 x 1000

..... = - 9003.9 mmols / L

So CO2 concentration in water = 9003.9 mmols /L

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