Question

What is the freezing point of a solution that contains 21.2g of urea,CO(NH2)2, in 265mL water,H2O? Assume a density of water of 1.00g/mol

Answer 1

you are going to need to calculate the molality of your soln, then figure out the ionization factor, then plug it into the freezing point despersion formula.

Answer 2

soln???

Answer 3

solution but when i'm in a hurry i write it soln, another common one i might do is rxn for reaction.

Answer 4

ohkayy. i REALLY need help with this problem because i have atest tomorrow & i have no idea how to do it -_-

Answer 5

Ok and i'm willing to help you figure this out but you have to figure out the things I tell you to, like first how many ions will Co(NH2)2 break into?

Answer 6

okay, thanks. it breaks into 3. Co, N & H

Answer 7

ok remember that number, now we need to find the molality of the soln.

\[molality=\frac{mole of solute}{kg solvent}\]

Answer 8

ΔT = (Kf)(m)(i), This is equation we are trying to find the different parts for

Answer 9

its actually 4..C,O,N,H

Answer 10

it's 3; Co and 2 NH, but see if you can get the molality figured out and I will try to find the constant we need

Answer 11

its CO not Co

Answer 12

the molalrity is C=12.
O=16
N2= 14 X 2= 28
H4=1X 4=4
so the malalrity is 60

Answer 13

that looks like the molar mass to me, now i would divide the amount of urea you have by the molar mass to get the moles of solute which will be in your soln.

Answer 14

so 4/60 right?

Answer 15

no it would be 21.2g/ 60g =?
divide that number by .265 and we will get the m value
m=1.33

Answer 16

\[\Delta T=1.86 * 1.33\]

Answer 17

\[\Delta T=2.48\]

now subtract that from waters normal freezing point and you get -2.48 degree celcius

Answer 18

yay thanks so much

Answer 19

Good luck on your test tomorrow, remember to figure out if you solute is ionic or molecular, because this changes up the equation slightly. Practice your molality they are big for these types of problems.