A solution is prepared by dissolving 38.6 g sucrose (C_12

Question

A solution is prepared by dissolving 38.6 g sucrose (C₁₂H₂₂O₁₁) in 495 g of water. Determine the mole fraction of sucrose if the final volume of the solution is 508 ml.

Accepted Answer

Hey everyone welcome back. So let's get started with this video. So here we're told 38.9 g of lactose is dissolved in g of water to a final volume of mL. And they want us to determine the concentration of the solution in the following units. Okay, so a is more clarity and recall that polarity is equal to most of salute over leader of solution. Okay, So then let's go ahead and figure out what everything in this question means. So then we have 38.9 g of lactose and it's being dissolved. So whatever is being dissolved is going to be our salute. Okay, so then ourselves, what? We just saw that it was lactose and it's being dissolved in 483 g of water. So where the soldier is being dissolved. That is going to be our solvent so that our solvent is going to be water and then the final volume that's going to be solidly opposed to solvent together. That's going to be our solution. Okay, so with this being said, we know we're going to need moles of solute over the leaders of solution. So leaders, a solution. That was going to be easy because we know the middle leaders. So then how do we go from the leaders to leaders? We divide by 1000 Or we can move the decimal back three times. So we have 496. Therefore it's going to equal zero 496 L. Okay, our salute. We're giving gramps for salute. So we can do is go to moles by using the molar mass of lactose. So then let's get started with the given. Which was the grams. 300 sorry, 38 0.9 g of lactose. Okay, molar mass is 300 .3 g of lactose and one more of lactose. So then grams cancel out. And we get zero point 11 36 more of lactose. Okay, So then since we found the moles of our salute is going to go in the numerator. 1136. So then we have most of our leader. We do the math and weekend zero point 2 to 9 polarity. So then we just solved for a. Okay, so now let's look at B. They want us to get the concentration and morality. So we call that morality is equal to moles of solitude over kilograms of solvent. Okay, so moses ali we actually sulfur it in the first one formula charity. So we use the same number. So then zero 11 36 more. Now, what we have to solve here is kilograms of solvent. We set our solvent is water and we're giving grams. So all we have to do is convert the grams to kilograms. So then we have 83 grams of water. And we know that 1000 g. Sorry, 1000 grimm's Is equal to one kg. So then grams cancel out and we get zero point 483. Kill the grounds of water. So then let's go ahead and plug this number in. So then we have moles over kilograms And we get zero point for morality. Okay, Let's look at the next one which is percent by mass. Okay, So then recall that percent by mass. That is equal to mass of solute over total mess. And since we're dealing with the%,, 100. Okay. So the masses who is lactose? And we're actually given the mass and we're told is 0.9 g total mass. That's going to be solid plus solvent. So then they're both in grounds and we know that the solvent is water. The solid is selected. So let's go ahead and add those values. So then we have Total mass of solid plus solvent. So 38 .9 From the Soul. You plus the solvent. 483. And these are all in grooms times 100. So then the grounds were canceled out And we would get seven point 45%. Okay, so then our next one is going to be more fraction. I recall that mole fraction is equal two moles of solute over total move and the total mold is going to equal the most of our salute, which is most of lactose plus the most over water. Okay, so the most associate we've been using that one in the past and we have it here and here. So let's go ahead and use the same number which is zero point total mall remember it's going to be solely plus solvent. So leo is lactose so it's going to be the same as the numerator. So that now we have to find the moles of our solvent and we're going to start with the given which is the grams because our solvent is water. So then grams of water. Going to use a moller mess. There's 18.02 g of water And one mole of water. So then we do the math and we get 26 more of water. Okay? So with that being said let's go ahead and add it in the denominator 26.80 More. So then the more would cancel out And we will get zero point 00 four and this is a more fraction and then finally our last one is more percent. So more percent is equal to moles solid over total moles times 100 Because it's 1%. So if you see here moses solely over total moles is the same as mole fraction. So then we can get the answer that we got and just multiply it by 100. So let's go ahead and put those numbers 0.00422 times 100 and we get zero point or 22%. Okay, Thank you for watching. I hope this helps, and I'll see you in the next video.

A solution is prepared by dissolving 38.6 g sucrose (C12H22O11) in 495 g of water. Determine the mole fraction of sucrose if the final volume of the solution is 508 ml.

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A solution is prepared by dissolving 38.6 g sucrose (C₁₂H₂₂O₁₁) in 495 g of water. Determine the mole fraction of sucrose if the final volume of the solution is 508 ml.