A solution prepared by dissolving 5.00 g of aspirin, C9H8O4, in 215 g of chloroform has a normal boiling point that is elevated by ΔT = 0.47 °C over that of pure chloro- form. What is the value of the molal boiling-point-elevation constant for chloroform?

Video transcript

Hey everyone, we're told when 36.3 g of ibuprofen with a molar weight of 206.3 g per mole is dissolved in 235 g of ethanol. The resulting solution boils, add 0.90 degrees Celsius higher than pure ethanol, calculate the value of our boiling point constant for ethanol. To answer this question, we have to use the following formula, which is the elevation of our boiling point for a solution is equal to our boiling point constant times our morality of our solution. Now, we were told that the elevation of our boiling point is 0.90°C. Now all we have to do is determine the morality of our solution in order to figure out our boiling point constant. To find our morality, We're going to go ahead and use dimensional analysis. Starting with 36.3 g of ibuprofen per 235g of ethanol, We're going to go ahead and take the molar weight of Ibuprofen, which we know to be 206.3 g of ibuprofen per one mole of ibuprofen. And since morality is in moles per kilogram, we're going to go ahead and convert our grams of ethanol into kilograms of ethanol. So we know that we have 10 to the 3rd g of ethanol per one kg of ethanol. So when we calculate this out and cancel out our units, We end up with a morality of 0.74875 mol per kilogram. Now let's go ahead and plug in our values. So we have our elevation of our boiling point, which is 0.90°C and this is going to be equal to our boiling point constant times. Our morality, which we calculated to be 0. mol per kilogram, Dividing both sides by our morality. We end up with a boiling point constant of 1. degrees Celsius times kilogram per mole. And this is going to be our final answer. Now, I hope this made sense and let us know if you have any questions.