An aqueous solution containing 100grams of dissolved MgSO4 is fed to a crystallizer where 80% of the Dissolved salt crystallises out as MgSO4. 6H2O Crystals. How many grams of the hexahydrate salt Crystals are obtained from the crystalliser?(given Mg=24; S=32; O=16 and H=1).
a) 80.
b) 152.
c) 120.
d) 100.
one gram of radioactive carbon took 5760 years to become 500mg ,it becomes 125 mg in
ans -11250 years xplain ,,,,,,,,,,how to get the ans
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2 Answers
1357for first
wt. of MgSO4=80 grams
moles of MgSO4=80/120=2/3
mole of water molecules=6*2/3=4
wt. of water =4*18=72 grams
so wt of MgSO4. 6H2O=80+72=152 gms
1357for second
500 mg =0.5 gram = half of 1 gram (initial amount)
so half life is 5760 years
it requires 3 half lives to become 0.125 grams
so time is 3*5760=17280 years
I don't know how the answer is 11250