Posted by Lauren on Wednesday, February 6, 2008 at 10:27pm.
Caffeine C8H10N4O2, is a stimulant found in a tea and coffee. A sample of the substance was dissolved in 45.0g of choloroform CHCl3 to give a 0.0946m solution. How many grams of caffine were in the sample.
m = molality
- Chemistry - drbob222, Wednesday, February 6, 2008 at 10:30pm
molality = m = mols/kg solvent.
mols = g/molar mass.
You have kg and m so use equation 1 to solve for mols.
then go to equation 2, plug in mols and molar mass and solve for grams.
- Chemistry - Lauren, Wednesday, February 6, 2008 at 10:35pm
ok i know how to figure out the 2nd equation
45.0g CHCl3(1 mols/118gCHCl3)=.381 mols CHCl3
but how do you get molarity. with kg solvent
- Chemistry - drbob222, Wednesday, February 6, 2008 at 11:25pm
You wrote a small m when you posted the question initially. m = molality not molarity.
Look at the definition I wrote above.
m = mols/kg solvent.
m(of caffeine) = mols caffeine/kg solvent
0.0946 = mols caffeine/0.045 kg CHCl3.
mols caffeine = ??
The g caffeine = mols carreine x molar mass caffeine = xx
check my work. (By the way, the molar mass CHCl3, which is not needed, is 119.4).
Answer This Question
More Related Questions
- Chemistry - Caffeine a stimulant found in coffee has the mass composition of C, ...
- biology - Caffeine is the most widely used stimulant in the world today. This ...
- statistics - The caffeine content of a cup of home-brewed coffee is a normally ...
- CHEMISTRY - 1.) A water sample is found to have 9.0 ppb of chloroform,CHCL3. How...
- Chemistry - A 0.84 g sample of caffeine, C8H10N4O2, burns in a constant-volume ...
- chemistry - What is the mass, in grams, of 7.40×1020 molecules of caffeine, ...
- Science - The pH of a 0.10-M solution of caffeine is 11.16. Determine Kb for ...
- Algebra - Hot Java Coffee Company adverties their decaffeinated coffee as 97% ...
- chemistry - Question #1 For a 170lb person, calculate the quanities of each of ...
- math - A cup of brewed tea has 54 milligrams less caffeine than a cup of brewed ...