Question

A solution is made by dissolving 10.20 grams of glucose (C6H12O6) in 355 grams of water. What is the freezing-point depression of the solvent if the freezing point constant is -1.86 °C/m? Show all of the work needed to solve this problem.

@ganeshie8 @dan815 @mathmale @jhonyy9 @chmvijay please help!! I've tried this so many times and it never comes out how I need it to. I really REALLY need help

Answer 1

you need to find an formula for this ?

Answer 2

What do you mean? Is it the molarity formula?

Answer 3

nope

Answer 4

I don't know then. I assumed you would have to do something with the boiling point elevation

Answer 5

Would it be Kb moles of solute/kg of solvent

Answer 6

?

Answer 7

@chmvijay you still there?

Answer 8

delta Tf = Kf * i * m

Answer 9

use this and try to find out :P

Answer 10

Could you plug in the numbers for me? I'm confused what "kf" "i" and "m" stand for

Answer 11

@chmvijay duuude

Answer 12

if i plug the numbers what will you do ?

Answer 13

Ok well can I show you what I got instead and you can tell me if it's right or not @chmvijay ? I think I figured it out. Just tell me if I did it correctly.

Answer 14

ok :) that's good :)

Answer 15

I'm 99.9% sure that's right

Answer 16

its 100 % right ;P

Answer 17

ok!! thank you<3 Can I ask another question?

Answer 18

yes please :) before that which one is you in ur pic :P

Answer 19

A solution is made by dissolving 2.5 moles of sodium chloride (NaCl) in 198 grams of water. If the molal boiling point constant for water (Kb) is 0.51 °C/m, what would be the boiling point of this solution? Show all of the work needed to solve this problem.

Answer 20

The one with the pink shorts on haha

Answer 21

similar way u need another formula relating the same stuff

Answer 22

ok please explain

Answer 23

have look at here
http://openstudy.com/study#/updates/5338d426e4b0b47fca869bf9

Answer 24

I did

Answer 25

I'm still confused

Answer 26

good :) lol what confuses you ?

Answer 27

He doesn't really give a good equation or anything to go off of. I have no idea what to even do in this problem @chmvijay

Answer 28

The examples given in my lesson dont help either. What equation do I have to use?

Answer 29

deltaTb = i* Kb* m
similar way to above ;P

Answer 30

k one sec, let me figure it out and then tell me if I did it right

Answer 31

good :)

Answer 32

i value u can use directly =2

Answer 33

what?

Answer 34

what do you mean you can use directly =2

Answer 35

deltaTb = i* Kb* m i value in this and find m from nacl and u know Kb ;)

Answer 36

Wait lol. What does "i" stand for? what does "m" stand for and what does ""kb" stand for?

Answer 37

Assuming complete dissociation of NaCl, 2 particles are produced in solution from each molecule of NaCl . i for vanthoffs factor and Kb is for molal boiling point constant for water and m for molaity

Answer 38

ok but how do you find those?

Answer 39

@chmvijay yeah, I'm confused. What are the numbers for each?

Answer 40

hello?

Answer 41

righ t:)

Answer 42

yeah ok but how did he get 106.4 ?

Answer 43

u find out :P

Answer 44

@chmvijay can you help me with another one?

Answer 45

Which of the following combinations will result in a reaction that is never spontaneous?

positive enthalpy change and positive entropy change

positive enthalpy change and negative entropy change

negative enthalpy change and positive entropy change

negative enthalpy change and negative entropy change