1) calculate how long it takes for 201Ti, with half life of 73.0 h, to decrease
ID: 801279 • Letter: 1
Question
1) calculate how long it takes for 201Ti, with half life of 73.0 h, to decrease from 888 to 111 counts/ minutes
2) calculate the percent(%) by mass of a solution that contains 1.05kg of NACL solute dissolved in 8.65* 10^(4)g of water solvent.
3) if a sample of Ar(g) contains 9.75 * 10^(2)ml at 4.44 atm and room T, then calculate the pressure, in atm, of this sample when it occupies 5.67L at room T.
4) when 12.00g of hydrogen and 122.0g of phophorus are allowed to react and all the hydrogen is used up as 88.8g of phosphine is formed while some phosphurus remains unreacted. calculate the mass of phosphorus that remains unreacted.
Explanation / Answer
1) Decay constant,? = ln2/t0.5 = 9.493*10^(-3) h-1
111 = 888*e^(-?t)
=> ?t = 3
=> t=3/? = 316.017 hrs
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2) Percentage by mass = 1.05/(1.05+86.5) *100 = 1.1422%
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3)PV = constant
=> Pfinal = 4.44*9.75*100/(5.67*1000) = 0.7635 atm)
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4) P4 + 6H2 -> 6PH3
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