I'm practicing for my lab final and I came across a question I do not understand...
If a 0.092 g sample of a 1:1 mixture of acetylferrocene and ferrocene was separated by column chromatography, and the recovered fractions weighed 0.019 g (acetylferrocene) and 0.020 g (ferrocene), what was the percent recovery of acetylferrocene ?
a. 20.6%
b. 41.3%
c. 21.7%
d. 43.5%
I thought the answer was (a) because .019/.092 x 100 = 20.7, but it is saying the answer is (b). Can anyone please explain this? Thank you.
Here is how it was done.
0.092 was the total mass of both materials. It was a 1:1 mixture; therefore, each had a mass of 0.092/2 = 0.046 g.
percent recovery then for the one compound is [0.019/0.046]*100 = 41.3%,
I think the secret word is "recovery." If we wanted the percent in the original mixture, then a would be correct; however, when we say recovery, that means, "how much did we get out of what we put in" and this approach usually means we want some quantitative number for the effectiveness of the procedure.
Thanks so much for the help, I didn't even consider what you mentioned!
Again, I really appreciate it!
To calculate the percent recovery of acetylferrocene, you need to compare the weight of the recovered acetylferrocene to the initial weight of the mixture.
Given:
Initial weight of the mixture = 0.092 g
Weight of recovered acetylferrocene = 0.019 g
To calculate the percent recovery of acetylferrocene, you can use the formula:
Percent recovery = (weight of recovered acetylferrocene / initial weight of the mixture) x 100
Plugging in the values:
Percent recovery = (0.019 g / 0.092 g) x 100 = 20.7%
From your calculation, the percent recovery of acetylferrocene is indeed 20.7%. Therefore, the correct answer should be (a) 20.6%, not (b) 41.3%. It seems like there might be an error in the answer choices or the solution provided to you.
To calculate the percent recovery of acetylferrocene, you need to divide the mass of the recovered acetylferrocene by the mass of the original mixture (0.092 g) and then multiply by 100 to express it as a percentage.
Let's perform the calculation:
Mass of recovered acetylferrocene = 0.019 g
Mass of original mixture = 0.092 g
Percent Recovery = (Mass of recovered acetylferrocene / Mass of original mixture) x 100
Percent Recovery = (0.019 g / 0.092 g) x 100
Percent Recovery ≈ 20.65
So, based on the calculation, the percent recovery of acetylferrocene should be approximately 20.65%. Therefore, your initial thought was correct, and the answer should be (a) 20.6%.
It is possible that there might be an error in the given answer choices, or in the information provided. I would suggest double-checking with your lab instructor or referring to any accompanying material or lecture notes to confirm the correct answer.