Many fish which normally line in mountain streams (where the water temperature i

Question

Many fish which normally line in mountain streams (where the water temperature is 0 degrees celcius) die when water in which they live warms up to 25 degrees C. How many oxygen molecules are there in 1.0 ml of water at these two temperatures? How much oxygen content change when the water is heated? Could this change in oxygen in oxygen content explain why fish die? Why or why not?

( Henry's Law constants at 0 C are k(O2)= 25400 bar , k(N2)= 54500 bar; and at 25 C k(O2)= 4400000000 Pa , and k(N2) = 8680000000 Pa)

Explanation / Answer

partial pressure of Oxygen = 0.21 atm ( since Oxygen is 0.21 fraction and air pressure = 1atm)

now for 1 ml water = 1gm water , moles of water = 1/18 = 0.05556

moles of oxygen = m . then mol fc of oxygen = m/(m+0.05556)

now at Oc   K = 25400 = P/x = 0.21/( m/(m+0.05556))

m/(m+0.05556) = 0.21/25400 = 0.00000827

m = 4.5935 x 10^-7 moles

Oxygen molecules at 1 ml = 4.5935 x10^-7 x 6.023x10^23 = 2.76669 x 10^17

at 25C K = 4400000000 = 0.21/(m/m+0.05556)

m = 2.6517 x 10^-12 ,

Oxygen molecules = 2.6517 x10^-12 x6.023x10^23   = 1.597 x 10^12

change in oxygen content when heated = ( 4.5935 x10^-7 -1.597 x10^-12) = 4.5934 x10^-7 moles

yes change in temperature could have caused fish death since there is large decrease in dissolved oxygen and oxygen levels became very low at 25C compared to 0C

fish survie on dissolved oxygen levels, when oxygen content is low fish can't survive

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