Question

. If N represents the number of atoms of a radionuclide in a sample at any given time, then the change dN in the number during a short time dt is proportional to N and to d Letting λ be the constant of proportionality (called the decay constant), we write: dN=-ANdt a. Why do we need the negative sign in this equation? b. What are the units of λ? c. From this equation, derive the exponential radioactive decay law/N = N, e 8. The equation derived in question 7 can also be used to calculate activity. Typically, N and No are replaced with A and Aa. Using the equation derived in question 7, calculate the activity of a 30 MBg Na- 22 sample after 2.5 years.


solve number 8

0 0
Add a comment Improve this question Transcribed image text
Answer #1

Given that

initial activity Ao=30 MBq

time t=2.5*years=2.5*365=912.5 days

half life T1/2=15 days

now we find the decay constant

decay constant \lambda=0.693/15=0.0462/days

now we find the activity

activity A=Aoe-\lambdat

=30*e^-0.0462*912.5

=1.5 MBq

Add a comment
Know the answer?
Add Answer to:
solve number 8 If N represents the number of atoms of a radionuclide in a sample...
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for? Ask your own homework help question. Our experts will answer your question WITHIN MINUTES for Free.
Similar Homework Help Questions
  • In all processes where a quantum system decays from a higher energy level to a lower...

    In all processes where a quantum system decays from a higher energy level to a lower one, the probability that the decay occurs during a given infinitesimal time interval dt is a constant, independent of time. Let us define this fixed probability to be adt, where is some constant (that has nothing to do with wavelength). This expresses the idea that at least for tiny time intervals, the probability is proportional to the duration of the interval: doubling the interval...

  • LOGISTI We know that if the number of individuals, N, in a population at time t follows an exponential law of growth, t...

    LOGISTI We know that if the number of individuals, N, in a population at time t follows an exponential law of growth, then N-N, exr where k >0 and No is the population when t -o. es that at time, t, the rate of growth, N, of the population is proportional to dt dN the number of individuals in the population. That is, kN Under exponential growth, a population would get infinitely large as time goes on. In reality, when...

  • Er counts the number of decays from a radioactive sample ina e interval Δt from a radioactive sou...

    could you do and explain part a er counts the number of decays from a radioactive sample ina e interval Δt from a radioactive source, starting at time t 0, The limiting n for this kind of experiment is the exponential distribution (5.69) wthere T is a positive constant. (a) Sketch this function. The distribution is zero for ent begins only at 0.) (b) Prove that this function satisfies the normalization condition (5.13). () Find the mean time T at...

  • The number of radioactive isotopes in a sample, N(t) as a function of time is given...

    The number of radioactive isotopes in a sample, N(t) as a function of time is given by an exponential law where N(0) is the initial number of radioactive isotopes at time t=0, and k is a constant. Find the expression for t1/f, the time it takes for N(t) to go from its initial value to N(o)/f. What is the value for X in the following expression?

  • As a radioactive specimen decays, its activity decreases exponentially as the number of radioacti...

    I only need help with part c). Thanks! As a radioactive specimen decays, its activity decreases exponentially as the number of radioactive atoms diminishes. Some radioactive species have mean lives in the millions (or even billions) of years, so their exponential decay is not readily apparent. On the other hand, many species have mean lives of minutes or hours, for their exponential decay is easily observed. According to the exponential decay law, the number of radioactive atoms that remain after...

  • what is the answer of 12 and 13 estimated as equivalent to that released by 20.000...

    what is the answer of 12 and 13 estimated as equivalent to that released by 20.000 tons of TNT. Assume 200 MeV is released when a 235 U nucleus absorbs a neutron and fission that 3.8 x 10' J is relensed during detonation of 1 ton of TNT. nuclear fissions occurred at Hiroshima, and what was the total de mass? utron and fissions and of 1 ton of TNT. How many was the total decrease in Scanned by CamScann 1.9...

  • Compute a Matlab script: Suppose we have two species of animals, foxes and rabbits and we wish to model their population Suppose the number of foxes at a given time is given by yn and the number o...

    Compute a Matlab script: Suppose we have two species of animals, foxes and rabbits and we wish to model their population Suppose the number of foxes at a given time is given by yn and the number of rabbits is given by rn. Suppose in the absence of predation, rabbits reproduce at a rate proportional to their population rn with constant of proportionality a. Suppose the rate at which foxes eat rabbits is proportional to the number of foxes with...

  • Applications of Exponential Equations Many real-life situations can be modeled by an exponential ...

    ANSWER ALL PLEASE! Applications of Exponential Equations Many real-life situations can be modeled by an exponential growth function of the form A(t) Ao ett constant that affects the rate of growth or decay, and t represents time. Using your knowledge of writing exponential equations that you did in the beginning of this chapter, what would A or an exponential decay function of the form A(t)-A ett where k represents the represent? 1. The amount of carbon-14 present in animal bones...

  • Review | Constants Periodic Table In the parts that follow, use the following abbreviations for time...

    Review | Constants Periodic Table In the parts that follow, use the following abbreviations for time If a substance is radioactive, this means that the nucleus is unstable and will therefore decay by any number of processes (alpha decay, beta decay, etc.). The decay of radioactive elements follows first-order kinetics. Therefore, the rate of decay can be described by the same integrated rate equations and half-life equations that are used to describe the rate of first-order chemical reactions: Measure of...

  • Review Constants Periodic a substance active times that the countable and will therefore decay by my...

    Review Constants Periodic a substance active times that the countable and will therefore decay by my name of processes the decay Del decay of the day of radioactive comm o der Therefore theme of daycan t orbed by the megrated w omen e n we used to describe the food chemical con In where the mo s t coloraty t he com by man of these quo ng 0. the world when contre long for fraction remaining - - (0.5)"...

ADVERTISEMENT
Free Homework Help App
Download From Google Play
Scan Your Homework
to Get Instant Free Answers
Need Online Homework Help?
Ask a Question
Get Answers For Free
Most questions answered within 3 hours.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT