##### 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.

### Solution: Click Here for Solution.

**Given:** O_{2} concentration in water required for fishes = 3.8 mg/L

Solubility of O_{2} in water = 2.2 × 10^{-3} mol/L

Pressure = 1 atm

**To find:** Partial pressure of O^{2} above the water needed for the survival of fish.

**Formula:** S = K_{H}P

**Calculation:** Pressure = 1 atm = 1.013 bar

Now, using formula and rearranging,

$\text{K}}_{\text{H}}=\frac{\text{S}}{\text{P}}=\frac{2.2\times {10}^{-3}\text{mol / L}}{1.013\text{bar}}=2.17\times {10}^{-3}{\text{mol L}}^{-1}{\text{bar}}^{-1$

O_{2} concentration in water required for fishes

= 3.8 mg/L = $\frac{3.8\times {10}^{-3}\text{g/L}}{32\text{g/mol}}=1.19\times {10}^{-4}{\text{mol L}}^{-1}$

Now, using formula and rearranging,

P = $\frac{\text{S}}{{\text{K}}_{\text{H}}}=\frac{1.19\times {10}^{-4}{\text{mol L}}^{-1}}{2.17\times {10}^{-3}{\text{mol L}}^{-1}{\text{bar}}^{-1}}$ = 0.0548 bar

The partial pressure of O_{2} above the water needed for the survival of fish is 0.0548 bar.

**Given:** O_{2} concentration in water required for fishes = 3.8 mg/L

Solubility of O_{2} in water = 2.2 × 10^{-3} mol/L

Pressure = 1 atm

**To find:** Partial pressure of O^{2} above the water needed for the survival of fish.

**Formula:** S = K_{H}P

**Calculation:** Pressure = 1 atm = 1.013 bar

Now, using formula and rearranging,

O_{2} concentration in water required for fishes

= 3.8 mg/L =

Now, using formula and rearranging,

P =

The partial pressure of O_{2} above the water needed for the survival of fish is 0.0548 bar.