Calculate the freezing point and boiling point of each aqueous
so...

Question

Calculate the freezing point and boiling point of each aqueous
solution, assuming complete dissociation of the solute.
c. 5.5% NaNO3 by mass (in water)

Accepted Answer

Hi everyone here, we have a question asking us to determine the boiling point and freezing point of an acquis solution. That is 8.70% potassium chlorate by mass, assume that potassium chlorate completely dissociates in water. So because it is 8.70% potassium chlorate by mass. We're going to assume that it's 100 g solution. So our mass of potassium chlorate Is 8.70 g. Our mass of our solution Is 100 g. So our massive water is 100g -8.70g, Which equals 91.3 g. Now, our morality equals moles of solute over kilograms of solvent. So our molar mass a potassium chlorate Equals 39.1 grams per mole plus 35.45 g per mole Plus 16.0 g per mole times three Equals 122. Graham's Permal, our moles of potassium chlorate Equals 8.70 g of potassium chlorate times one mole Over its molar mass. So 122 .55g. And our grams here are canceling out and that equals zero .07099 moles. potassium chlorate. Our mass of water Equals 91.3 g of water times one kg Divided by 10 to the 3rd g. So are grams here are canceling out And that equals 0.0913 kg. Now, actually calculating our morality, our morality equals 0. moles of potassium chlorate Divided by 0.0913g kg And that equals 0.777 morality. Now our potassium chlorate, it told us to assume that it completely disassociate. So we're going to assume it completely dissociates into potassium plus chlor eight, Meaning it's an electrolyte, meaning our van Hoff factor equals two. So our change in boiling point equals the boiling point of the solution minus the boiling point of our peer solvent. So the change in boiling point equals r. Van Hoff factor times our boiling point constant times our morality and our boiling point constant equals 0.512 degrees Celsius per morality, our boiling point of our peer solvent Equals 100°C. So our change in boiling point equals two Times 0.512°C per morality Times 0.777 Morality Equals 0.796°C. Our change in boiling point solution equals the change in boiling point plus the boiling point of our pure solvent Equals 100°C plus 0.796 degrees Celsius equals point seven at 96°C. And that is our first answer. And now to calculate the freezing point, the change in our freezing point is going to equal the freezing point of our solvent minus the freezing point of our solution. The change in freezing point is going to equal our van Hoff factor times our freezing point constant times our morality Are freezing point constant equals 1.86°C. over morality, Our freezing point of our peer solvent equals 0°C. So our change in freezing point equals two Times 1. degrees Celsius over morality times 0.777 morality Equals 2.890°C. So our freezing point of our solution equals our freezing point of our solvent minus the change in freezing point, So that equals 0°C -2.890°C. That equals negative 2.890°C. And that is our second and final answer. Thank you for watching. Bye.

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