Fish generally need an O2 concentration in water of at least 4 mg/L for survival. What partial pressure of oxygen above the water in atmospheres at 0 °C is needed to obtain this concentration? The solubility of O2 in water at 0 °C and 1 atm partial pressure is 2.21 * 10-3 mol>L.

Video transcript

Hey everyone, we're told that the established warning level of methane and water is 10 mg/s, determine the partial pressure of methane and atmospheric pressure above water required to achieve this concentration at 25°C. The Henry's law constant for methane at 25°C is 1.5 times 10 to the negative third mole per leader times atmospheric pressure. To answer this question, we need to use the following formula which is the soluble itty of methane is equal to our Henry's law constant, times the partial pressure of methane. Now they've given us our Henry's law constant and all we need to do is determine the solid ability of methane in order to get our partial pressure To solve for the cell viability of methane, we're simply going to use dimensional analysis, starting with the established warning level of methane and water, which is 10 milligrams per leader. Now we want to convert this into grams and we know that we have 10 to the third milligrams per one g. Next. Using the molar mass of methane, We know that we have 16.04 g of methane Per one Mole of Methane. Now, when we calculate this out and cancel out our units, we end up with a solid ability of 6.2344, 1 times 10 to the negative four mol per leader. Now let's go ahead and solve for the partial pressure of methane. All we need to do is take the salt ability of methane and divide this by our Henry's law constant. So, plugging in our values, we have our cell ability of methane which we calculated to be 6. 344, 1 Times 10 to the -4 moles per liter. Next we're going to divide this by our Henry's law constant value, which was 1.5 times 10 to the negative third mole per leader times atmospheric pressure. Now, when we calculate this out And cancel out our units, we end up with a partial pressure of 0.4 to atmospheric pressure, which is going to be our final answer. Now, I hope that made sense and let us know if you have any questions.