Homework Help: chemistry

Posted by Anna King on Sunday, February 5, 2012 at 6:05pm.

A solution was made by dissolving 62.07 grams of a compound in 500.0 g of water. The compound was not ionic. The freezing point of the solution was measured and found to be – 1.86oC. Using the Kf value in your textbook , the molar mass of this compound can be calculated to be

a) 57.7 g/mol
b) 124 g/mol
c) 231 g/mol
d) 62.1 g/mol
e) 115 g/mol

bet its e

chemistry - DrBob222, Friday, February 3, 2012 at 6:34pm
If you were betting you lost.
delta T = i*Kf*m
You know dT, i = 1, and Kf. Solve for molality.
Molality = moles/kg solvent.
You have m and kg solvent, solve for moles.

moles solute = n = grams solute/molar mass solute.
You know moles and grams, solve for molar mass.

still lost :(

chemistry - MathMate, Sunday, February 5, 2012 at 7:23pm
From Dr. Bob's hints, you have

Δ T = i*Kf*M
where M is the number of moles

ΔT = 1.86 °C
i=1
Kf=1.86 °C/m for non-ionizing solutes (check value from your book)

M=ΔT/(i*Kf) mole

Equate this to the mass of solute per 1000 ml. of solution, which we have to assume that the volume of solution equals the volume of water initially to get

M m/l= 62.07/0.5 g/l.
So molar mass
= (62.07/0.5)/M

Answer this Question

Related Questions

chemistry - A solution was made by dissolving 62.07 grams of a compound in 500.0...
Chemistry - A solution was made by dissolving 62.07 grams of a compound in 500g ...
Chemistry - A solution was made by dissolving 62.07grams of a compound in 500g ...
chemistry - The solubility of an ionic compound is 30 grams of compound in 100 ...
chemistry - A solution is prepared with an unknown compound with an empirical ...
Chemistry - A dilute aqueous solution of an organic compound soluble in water is...
Chemistry - A solution is prepared by dissolving 130 g of NaNO3 in 100 g of ...
Chemistry - A solution is prepared by dissolving 130 g of NaNO3 in 100 g of ...
Chemistry - A certain compound contains carbon, hydrogen , and oxygen. When 1.00...
Chemistry - A certain compound contains carbon, hydrogen , and oxygen. When 1.00...

For Further Reading

First Name:
School Subject:
Answer: