# Maximum Percent Recovery of pure acetanilide?

• JameB
In summary: If you really wanted to be sure you could look up the solubility of your material in cold water but that's probably not necessary. In summary, the solubility of acetanilide in water at 100C is 5.5g/100mL and at 0C is 0.53g/100mL. A 0.150g sample of acetanilide was recrystallized in 3mL of hot water, resulting in a maximum possible percent recovery of 90.9%. If the crystals were washed with 20mL of ice cold water during vacuum filtration, the percent recovery would be reduced by 64.2%. The relevant equations used were the percent
JameB

## Homework Statement

Solubility of acetanilide in water is
5.5g/100mL at 100C
0.53g/100mL at 0C

A 0.150g sample of acetanilide containing only traces of impurities was recrystalized using a total of 3mL of hot water.

a) What is the maximum possible percent recovery of pure acetanilide? Show all steps...

b) By how much would the % recovery be reduced if, during vacuum filtration, the crystals were washed with a total of 20mL of ice cold water?

## Homework Equations

Percent recovery equation and basic mathematical operations...

## The Attempt at a Solution

for a) :=
mass that was recrystallized is 0.150g (is this correct assumption?)
maximum acetanilide that could dissolve in water at 100C is 0.165g (100mL = 5.5g then how much is 3mL...)

which implies that max recovery is (0.15/0.165)*100% = 90.9%

Is this right??!

for b) :=
amount that could dissolve in 20mL cold water= 20*0.53/100 = 0.106g

which implies that amount recovered = 0.150-0.106g = 0.044g

which implies that percent recovery is 0.044/0.165*100 = 26.7%

which means that % recovery will be reduced by 64.2%

Am I correct? Thanks :)

JameB said:

## Homework Statement

Solubility of acetanilide in water is
5.5g/100mL at 100C
0.53g/100mL at 0C

A 0.150g sample of acetanilide containing only traces of impurities was recrystalized using a total of 3mL of hot water.

a) What is the maximum possible percent recovery of pure acetanilide? Show all steps...

b) By how much would the % recovery be reduced if, during vacuum filtration, the crystals were washed with a total of 20mL of ice cold water?

## Homework Equations

Percent recovery equation and basic mathematical operations...

## The Attempt at a Solution

for a) :=
mass that was recrystallized is 0.150g (is this correct assumption?)
maximum acetanilide that could dissolve in water at 100C is 0.165g (100mL = 5.5g then how much is 3mL...)

which implies that max recovery is (0.15/0.165)*100% = 90.9%

Is this right??!

You are using the solubility of this material at 100C which is good to know but when you recrystallize it the temperature is lowered to near freezing (if you are doing it right). So how much would you lose in 3mL of water at 0C?

chemisttree said:
You are using the solubility of this material at 100C which is good to know but when you recrystallize it the temperature is lowered to near freezing (if you are doing it right). So how much would you lose in 3mL of water at 0C?

I would lose 0.0159 at 0C from 0.150g right? (or from 0.165g?)

if I lose 0.0159 then my max percent recovery is [(0.150-0.0159)/0.150]*100=89.4%

Yes?

I'm not going to check your math but using the cold water solubility is certainly the way to go.

I would like to provide the following response to this content:

Your calculations and assumptions seem to be correct for both parts a) and b). However, it is important to note that these calculations are based on ideal conditions and may not necessarily reflect the actual experimental results. Factors such as human error, impurities in the original sample, and imperfect recrystallization techniques can all affect the final percent recovery. It is also important to consider the solubility of acetanilide in the solvent used for recrystallization, as this can greatly affect the maximum possible percent recovery. Overall, while your calculations provide a good estimate, it is important to keep in mind that the actual results may vary.

## 1. What is the purpose of determining the maximum percent recovery of pure acetanilide?

The maximum percent recovery of pure acetanilide refers to the highest possible amount of pure acetanilide that can be obtained from a given sample. This information is important in determining the efficiency of a purification process and the quality of the resulting product.

## 2. How is the maximum percent recovery of pure acetanilide calculated?

The maximum percent recovery of pure acetanilide is calculated by dividing the actual yield of pure acetanilide by the theoretical yield, and then multiplying by 100. The theoretical yield is the amount of pure acetanilide that would be obtained if the purification process was 100% efficient.

## 3. What factors can affect the maximum percent recovery of pure acetanilide?

Several factors can affect the maximum percent recovery of pure acetanilide, including the purity of the starting material, the efficiency of the purification process, and the skill of the person performing the purification. Contaminants and impurities in the starting material can also lower the maximum percent recovery.

## 4. How can the maximum percent recovery of pure acetanilide be improved?

The maximum percent recovery of pure acetanilide can be improved by using a higher purity starting material, optimizing the purification process, and minimizing sources of contamination. Proper techniques and equipment should also be used to ensure the best possible recovery.

## 5. Is the maximum percent recovery of pure acetanilide always 100%?

No, the maximum percent recovery of pure acetanilide is not always 100%. Factors such as human error, imperfect purification techniques, and impurities in the starting material can prevent a 100% recovery. However, a high percentage of recovery is desirable and indicates a successful purification process.