# General chemistry Q

#### 299678

##### Guest
The Kb is 1.78 for 1 kilogram of aceton. What is the value of Delta Tb for 100 grams of acetone?

#### sfoksn

10+ Year Member
I am not sure how to solve this, because they should give you the volume of the solvent. Otherwise, we don't know the molality and cannot calculate the Tb...

What does the solution say?

#### qkchen

7+ Year Member
kpark102, does the answer involve a colligative property, such as melting point depression?

OP
2

#### 299678

##### Guest
The Kb is 1.78 for 1 kilogram of aceton. What is the value of Delta Tb for 100 grams of acetone?

My calculation as follows:
Tb = Kb x mass x i Since aceton is non electrolytes, so i = 1, so TB = Kb x mass
100 g x (1.78 / 1000g ) so 0.178, but solution said 1.78 so I posted it here

#### sfoksn

10+ Year Member
you can't really solve this... right? not information given, I think.

Don't we have to know the molality to solve colligative properties?

EVen though we know that it is 1kg of acetone solution, it could be 10 molality or 1 molality. we can't just assume anything...

anyone know how to solve this?

OP
2

#### 299678

##### Guest
I wrote exactly same word by word

#### oae

##### New Member
10+ Year Member
7+ Year Member
i got .178 as well. What source is question from? Possibly theyve marked the incorrect answer for being right?

#### sfoksn

10+ Year Member
Can you guys please tell me how you solved for this problem?

Thank you.

#### TexasOMFS

5+ Year Member
The Kb is 1.78 for 1 kilogram of aceton. What is the value of Delta Tb for 100 grams of acetone?

My calculation as follows:
Tb = Kb x mass x i Since aceton is non electrolytes, so i = 1, so TB = Kb x mass
100 g x (1.78 / 1000g ) so 0.178, but solution said 1.78 so I posted it here
The boiling point elevation equation is Delta Tb=Kb*m*i, where m stands for molality, not mass. It's a badly worded question, just throw it out.

#### sfoksn

10+ Year Member
Texas, exactly my point.

so there is no way we can know the molality from the info that the problem gives us, correct?