A sample of 2.3*1010 atoms that decay by alpha emission has a half-life of 150
min. How many alpha particles are emitted between t=30 min and t=160 min?
The mass of a radioactive substance reduces to 0.9 of its initial value in 5 hours.
What is the half life of this substance?
Any help would be appreciated!! THANKS
min. How many alpha particles are emitted between t=30 min and t=160 min?
The mass of a radioactive substance reduces to 0.9 of its initial value in 5 hours.
What is the half life of this substance?
Any help would be appreciated!! THANKS
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The number of particles left in a decaying substance is given by the equation:
Ae^(-λt)
A is the start number of particles
λ is the decay constant
t is time
Here's another equation relating the decay constant and the half life:
ln(2) / λ = T(1/2)
T(1/2) is the half life
For the first problem A = 2.3x10^10 and you can solve for the decay constant to get λ = .00462
Plug in t = 30 and t = 160 to the equation and find the difference between these two values. That is the number of alpha particles emitted between those time periods.
It ends up being: 9.04x10^9 alpha particles
For the second problem you can just set A = 1 and set the equation equal to 0.9 and solve for the decay constant, which you could then use to find the half life.
It ends up being: 32.9 hours
Ae^(-λt)
A is the start number of particles
λ is the decay constant
t is time
Here's another equation relating the decay constant and the half life:
ln(2) / λ = T(1/2)
T(1/2) is the half life
For the first problem A = 2.3x10^10 and you can solve for the decay constant to get λ = .00462
Plug in t = 30 and t = 160 to the equation and find the difference between these two values. That is the number of alpha particles emitted between those time periods.
It ends up being: 9.04x10^9 alpha particles
For the second problem you can just set A = 1 and set the equation equal to 0.9 and solve for the decay constant, which you could then use to find the half life.
It ends up being: 32.9 hours