Decays per second, finding mass

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SUMMARY

The discussion focuses on calculating the mass of a sample of (35/16)Sulfur based on its decay rate of 3.52*10^5 decays per second and a half-life of 7.55*10^6 seconds. The decay constant (lambda) is derived using the formula lambda = 0.693 / t(1/2), resulting in a value that is then used to find the number of atoms (N). The user attempted to calculate the mass by dividing the decay rate by lambda, converting to moles using Avogadro's number, and then multiplying by the molar mass of 35 g/mol. However, the user reported that this method did not yield the correct mass.

PREREQUISITES
  • Understanding of radioactive decay and half-life concepts
  • Familiarity with the decay constant calculation
  • Knowledge of Avogadro's number and its application in mole calculations
  • Basic proficiency in algebra for manipulating equations
NEXT STEPS
  • Review the calculation of the decay constant using lambda = 0.693 / t(1/2)
  • Learn about the relationship between decay rate and number of atoms in a sample
  • Study the conversion process from atoms to moles using Avogadro's number
  • Explore the implications of molar mass in mass calculations for radioactive samples
USEFUL FOR

This discussion is beneficial for students studying nuclear chemistry, particularly those tackling problems related to radioactive decay and mass calculations. It is also useful for educators and tutors assisting learners in understanding these concepts.

ronpaulkid
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Homework Statement


The activity of a sample of (35/16)Sulfur with a t(1/2) of (7.55*10^6 s) is 3.52*10^5 decays per second.

What is the mass of the sample?

Homework Equations



N=Noe^-lambda*t
lambda=.693/(t1/2)
No/DeltaT=lambda*N

The Attempt at a Solution



My attempt was to use the decays per second given in the equation and divide by lambda which is calculated from (.693/(7.55*10^6s). This will give you an answer N. From there I divided by avogadros number to find moles and then multiplied by the molar mass (35g/mol) to find grams. Didn't work.
 
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This should work. What answer did you get and what do you think is the right answer?
 

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