# Chemistry

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

1. 👍
2. 👎
3. 👁
1. 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.

1. 👍
2. 👎
2. 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

1. 👍
2. 👎
3. 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).

1. 👍
2. 👎

## Similar Questions

2. ### Calculus

The temperature of a cup of coffee varies according to Newton's Law of Cooling: dT/dt = -k(T - A), where T is the temperature of the tea, A is the room temperature, and k is a positive constant. If the water cools from 100°C to

3. ### Chemistry

A substance has a molecular formula of C8H10N4O2. The empirical formula is -

4. ### Chemistry

Caffeine a stimulant found in coffee has the mass composition of C, 49.48%, H, 5.19%, N, 28.85%, O 16.48%. The molar mass of caffeine is 194.19g/mol. Find the molecular formula for caffeine.

1. ### calculus

Carbon-14 is a radioactive substance produced in the Earth's atmosphere and then absorbed by plants and animals on the surface of the earth. It has a half-life (the time it takes for half the amount of a sample to decay) of

2. ### math

In a random sample of 75 individuals, it was found that 52 of them prefer coffee to tea. What is the margin of error for the true proportion of all individuals who prefer coffee?

3. ### Organic Chemistry

1) Calculate the partition coefficient of caffeine in water/methylene chloride from the following data: 10.3 g/100 mL for methylene chloride and 2.04 g/100 mL for water. 2. A student is sure that 0.500 grams of caffeine is

4. ### Statistics: Calculate a Pearson's r

In a study on caffeine and stress, college students indicated how many cups of coffee they drink per day and their stress level on a scale of 1 to 10. The data are provided in the following table. Number of Cups of Coffee 3, 2, 4,

1. ### MATH!

The mass of a radioactive substance follows an exponential decay model, with a decay rate of 5% per day. A sample of this radioactive substance was taken six days ago. If the sample has a mass of 3 kg today, find the initial mass

2. ### Math

When you drink a cup of coffee or a glass of cola, or when you eat a chocolate bar, the percent, P, of caffeine remaining in your bloodstream is related to the elapsed time, t, in hours, by t=5(logP/log0.5). a) how long will it

3. ### Statistics

A coffee company wants to make sure that there coffee is being served at the right temperature. If it is too hot, the customers could burn themselves. If it is too cold, the customers will be unsatisfied. The company has

4. ### statistics

In a study of caffeine and stress, college students indicate how many cups of coffee they drink per day and their stress level on a scale of 1-10. The data appear below. Number of Cups of Coffee Stress Level 3 5 2 3 4 3 6 9 5 4 1