# chemistry

posted by Jon

1. You are given a mixture containing two compounds, A and B. Both compounds have a solubility of 1 g/ 100 mL of solvent at 20 °C and 16 g/ 100 mL of solvent at 100 °C. The sample is composed of 3.5 g of A and 10 g of B. At 100 °C the entire sample just dissolves in a minimum amount of solvent. The solution is cooled to 20 °C and crystals are collected. Calculate the composition of the crystals and the yield of the process. What is the composition of the mother liquor?
2. If the crystals obtained in question (2) are recrystallized from 100 mL of solvent, what will be the yield and composition of the crystals obtained?

1. ob

yudyjutybttyjdk yui7 8y i76d iryu

2. Marisol

At 100 degrees celsius Compound B (Has the greater mass): 10g x 100mL/16g = 62.5mL When cooled to 20 degrees celsius Compound A: 62.5mL x 1g/100mL = 0.625g Compound B: 62.5mL x 1g/100mL = 0.625g Therefore the mother liquor contains 0.625g of each. Composition of crystal Compound A = 3.5g - 0.625g = 2.875g Compound B = 10g – 0.625g = 9.375g Percent Yield Compound A = 2.875g/(2.875+9.375)g x 100% = 23.5% Compound B = 9.375g/(2.875+9.375)g x 100% = 76.5% % yield of process = (2.875+9.375)g/(3.5+10)g x 100% = 12.5g/13.5g x 100% = 90.7%

## Similar Questions

1. ### Low recovery

The question is: A student performs a crystallization on an impure sample of biphenyl. The sample weighs 0.5g and contains about 5% impurity. Using his knowledge of solubility, he decides to use benzene as a solvent. The final weight …
2. ### science(chem)

Consider the following errors that could be made when running the TLC. Indicate what should be done to correct the error. a) A 2 component mixture containing 1-octene and 1,4- dimethylbenzene gave only 1 spot with and Rf value of 0.95. …
3. ### chemistry

Consider a set of compounds called carboxylic acids which have the general formula CH3(CH2)nCO2H. As the value of n in the formula increases from zero to 10, what happens to the solubility of these compounds in water?
4. ### Organic Chemistry

Compound A is recrystallized from n-propanol. Given are the following solubilities (in 100 mL of solvent): 160 g/100 °C, 100 g/80 °C, 60 g/60 °C, 20 g/20 °C, 15 g/10 °C and 10 g/0 °C. How many milliliters of solvent are needed …
5. ### Organic Chemistry

Referring to solvent mixtures, which statements are TRUE ?
6. ### Chemistry

For the Following sets of compounds determine the best solvent, by looking at structure, also by looking at solubility vs. temp. Which is the best solvent for crystalization, in which the compound is too soluble, and in which solvent …
7. ### Chemistry

Assume your sample spots are 1 cm above the bottom of the TLC plate. What happens if you put the plate in a developing chamber that has 1.2 cm of developing solvent?
8. ### Chemistry

The solubility of compound A in ethanol is 0.4 g per 100 mL at 0C and 5.0 g per 100 mL at 78C. What is the minimum amount of solvent needed to recrystallize an 8.0 g sample of compound A?
9. ### chemistry

help please, have no clue how to solve this. (a) you are given a mixture containing two compounds, A and B. both compounds have a solubility of 1g/100mL of solvent at 20 deg C and 16g/100mL of solvent at 100 deg C. The sample is composed …
10. ### Chemistry

A sample of plant extract is subjected to thin layer chromatography using aluminum backed plates of 0.25 mm thickness. The sample extract is suspected to contain a series of related compounds with hydroxyl and ester functional groups. …

More Similar Questions