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Radon (Rn) is the heaviest and the only radioactive member of Group 8A(18), the

ID: 892765 • Letter: R

Question

Radon (Rn) is the heaviest and the only radioactive member of Group 8A(18), the noble gases. It is a product of the disintegration of heavier radioactive nuclei found in minute concentrations in many common rocks used for building and construction. In recent years, health concerns about the cancers caused from inhaled residential radon have grown. If 1.00 Times 10^15 atoms of radium (Ra) produce an average of 1.373 Times 10^4 atoms of Rn per second, how many liters of Rn, measured at STP, are produced per day by 1.25 g of Ra? L Rn/day

Explanation / Answer

no of moles = (1.25/226) = 0.00553 mole

1 mole = 6.023*10^23 atom/mol

atomicmass of Ra = 226 g/mol

No of atoms of Ra = (1.25/226)*6.023*10^23 = 3.31*10^21 atoms


1*10^15 atoms gives 1.373*10^4 atoms/sec

so that,

3.31*10^21 atoms gives = (1.373*10^4)*(3.31*10^21)/(1*10^15)

     = 4.54463*10^10 atoms/sec

No of atoms produced per day = (4.54463*10^10 *86400)

    = 3.92656032*10^15 atoms/day

volume V = nRT/P

STP ,

P = 1 atm , T = 273 K

n = no of moles = (3.92656032*10^15/(6.023*10^23))

   = 6.52*10^-9 mole

V = (6.52*10^(-9))*0.0821*273/1

= 1.46134716*10^-7 L Rn/day