Nuclear Chemistry (determing masses from radioactive decay)

Click For Summary
SUMMARY

This discussion focuses on calculating the fraction of threonine recovered from a hydrolyzed protein sample using radioactive decay principles. A 2.80 mg sample of 14C-labeled threonine with an initial activity of 1950 dpm was analyzed, yielding a pure threonine sample with an activity of 550 dpm. The decay constant for the threonine sample was determined to be 1.375E-16, and the mass of the recovered threonine was calculated to be 0.789 grams. The discussion emphasizes the importance of understanding radioactive decay and mass calculations in nuclear chemistry.

PREREQUISITES
  • Understanding of radioactive decay and decay constants
  • Familiarity with chromatographic separation techniques
  • Knowledge of molar mass calculations
  • Proficiency in using activity measurements in nuclear chemistry
NEXT STEPS
  • Study the principles of radioactive decay and its applications in chemistry
  • Learn about chromatographic techniques for amino acid separation
  • Explore calculations involving Avogadro's number and molar mass
  • Investigate the implications of half-lives on radioactive sample analysis
USEFUL FOR

This discussion is beneficial for chemistry students, nuclear chemists, and researchers involved in protein analysis and radioactive labeling techniques.

Quickman08
Messages
1
Reaction score
0
I have been trying for quite some while but I can't seem to get this problem off the ground.1)Suppose that you hydrolyze 4.644 grams of a protein to form a mixture of different amino acids. To this is added a 2.80 mg sample of 14C-labeled threonine (one of the amino acids present).The activity of this small sample is 1950 dpm. A chromatographic separation of the amino acids is carried out, and a small sample of pure threonine is separated. This sample has an activity of 550 dpm. What fraction of the threonine present was separated? What is the total amount of threonine in the sample?

2)
I know that 1950dpm= 8.783E-10Ci and 550dpm=2.477E-10Ci
I am not sure if you need it but the molar mass of Threonine is 119.12 g mol−1
Also A=Lambda(N)
m=(N/Ao)*(MM)
A=radioactive mass units
Lambda=decay constant
N=number of atoms
Ao=avogadro's number
MM=molar mass3.
I have found the decay constant for the small sample of 2.80mg to be 1.375E-16
So if you take the 550dpm sample you can obtain a mass of .789g
Unfortunately once this mass is obtained I cannot figure out where to go from this point.
 
Last edited:
Physics news on Phys.org
Don't worry about decay, assume sample activity is constant. It never is, but if half lives are long enough, that's a valid assumption.

You started with 1950 dpm, you have 550 dpm. What part of the radioactive threonine was recovered?
 

Similar threads

Radioactive decay of Uranium 238
  • · Replies 7 ·
Replies
7
Views
3K
Undergrad What is the Process and Mathematical Explanation of Radioactive Decay?
  • · Replies 1 ·
Replies
1
Views
2K
KE of alpha particle using integer values of nuclear masses
  • · Replies 23 ·
Replies
23
Views
3K
Decays per second, finding mass
  • · Replies 1 ·
Replies
1
Views
5K
Radioactivity & Specific Heat Capacity Question
  • · Replies 3 ·
Replies
3
Views
4K
Graduate What Are the Key Concepts of Mass Defects in Nuclear Reactions?
  • · Replies 1 ·
Replies
1
Views
4K