Fish generally needs O2 concentration in water at least 3.8 mg/L for survival. What partial pressure of O2 above the water is needed for the survival of fish? - Chemistry

Exercise | Q 8 | Page 46

Fish generally needs O2 concentration in water at least 3.8 mg/L for survival. What partial pressure of O2 above the water is needed for the survival of fish? Given the solubility of O2 in water at 0 °C and 1 atm partial pressure is 2.2 × 10-3 mol/L.

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Given: O2 concentration in water required for fishes = 3.8 mg/L
Solubility of O2 in water = 2.2 × 10-3 mol/L
Pressure = 1 atm

To find: Partial pressure of O2 above the water needed for the survival of fish.

Formula: S = KHP

Calculation: Pressure = 1 atm = 1.013 bar

Now, using formula and rearranging,

KH=SP=2.2×10-3mol / L1.013 bar=2.17×10-3mol L-1bar-1

O2 concentration in water required for fishes

= 3.8 mg/L = 3.8×10-3g/L32 g/mol=1.19×10-4mol L-1

Now, using formula and rearranging,

P = SKH=1.19×10-4mol L-12.17×10-3mol L-1bar-1 = 0.0548 bar

The partial pressure of O2 above the water needed for the survival of fish is 0.0548 bar.