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Confused :/ Many fish which normally live in mountain streams (where the water t

ID: 797636 • Letter: C

Question

Confused :/

Many fish which normally live in mountain streams (where the water temperature is 0degreeC) die when the water in which they live warms up to 25degreeC. How many oxygen molecules are there in 1.0 mL of water at these two temperatures? How much does the oxygen content change when the water is heated? Could this change in oxygen content explain why the fish die? Why or why not? (Henry's Law constants at 0degreeC are k(O2) = 2.54 *104 bar, k(N2) = 5.45 *104 bar; and at 25degreeC k(02) = 4.40 *109 Pa, k(N2) = 8.68 *109 Pa.)

Explanation / Answer

partial pressure of oxygen in air = 0.21 atm = 0.21*1.01325 bar = 0.212782 bar

at 0 C

conc of O2 in water = P/K(O2) = 0.21*1.01325/2.54*10^4

= 8.37*10^-6 M

no of molecules in 1 ml of water = (6.023*10^23)*(8.37*10^-6)*(10^-3)

= 5.05*10^15 molecules

at 25 C

conc of O2 in water = P/K(O2) = 0.21*1.01325/4.40*10^4

= 4.84*10^-6 M

no of molecules in 1 ml of water = (6.023*10^23)*(4.84*10^-6)*(10^-3)

= 2.91*10^15 molecules

change in oxygen content = 2.14*10^15 molecules

change in oxygen content might be one of the reason but there are other factorss like pH or sometimes temp change can kill them