In 5.49 seconds, 1.20 g of argon-35 decays to leave only .15 g. What is the half life of argon-35?

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Answer 1 · 2016-05-22T07:49:58

1.83 sec

#m_i=m_r*2^n#

#m_i " is the initial mass present of the radioisotope."#

#m_r" is the mass remaining after a certain time "#

#n " is the number of periods," = (time)/T" where T is the half-life."#

#m_i=m_r*2^n#

#m_i/m_r=2^n#

#2^n=(1.20\ g)/(0.15\ g)#

#2^n=8#

#2^n=2^3#

#" "color(red)ulbar(color(black)(n=3))#

#n= (time)/T" #

#T "(half-life)"= (time)/n#

# T = (5.49 sec)/3#

# color(blue)(ulbar(color(red)(T = 1.83" sec"))#