General chemistry Q

[299678]

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

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[sfoksn]

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]

kpark102, does the answer involve a colligative property, such as melting point depression?

 

[299678]

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]

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?

 

[299678]

I wrote exactly same word by word

 

[oae]

i got .178 as well. What source is question from? Possibly theyve marked the incorrect answer for being right?

 

[sfoksn]

Can you guys please tell me how you solved for this problem?

Thank you.

 

[TexasOMFS]

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]

Texas, exactly my point.

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