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Steph191290
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A scientist wishes to find the age of a sample of rock. Realising that it contains radioactive potassium, which decays to give a stable form of argon, the scientist started by making the following measurments:
decay rate of the potassium in the sample = 0.16Bq
mass of potassium in the sample = 0.6x10^-6g
mass of argon in the sample = 4.2x10^-6g
The Molar mass of the potassium is 40g. show that the decay constant for potassium is 1.8x10-17 and its half-life is 1.2x10^9years.
decay constant = a/N
n=m/Mr
N=m/Mr
N=0.6x10^-6/40
N=1.5x10^-8
N=1.5x10^-8 x 6.02x10^-8
N=9.03 x 10^-16
decay constant = a/N
decay constant = 0.16/9.03x10^-16
I got this far then got stck as the answer was wrong, I am not sure wher to go from here any help would be appreciated.
decay rate of the potassium in the sample = 0.16Bq
mass of potassium in the sample = 0.6x10^-6g
mass of argon in the sample = 4.2x10^-6g
The Molar mass of the potassium is 40g. show that the decay constant for potassium is 1.8x10-17 and its half-life is 1.2x10^9years.
Homework Equations
decay constant = a/N
n=m/Mr
The Attempt at a Solution
N=m/Mr
N=0.6x10^-6/40
N=1.5x10^-8
N=1.5x10^-8 x 6.02x10^-8
N=9.03 x 10^-16
decay constant = a/N
decay constant = 0.16/9.03x10^-16
I got this far then got stck as the answer was wrong, I am not sure wher to go from here any help would be appreciated.