The normal boiling point (i.e boling point at 1 atm = 1.013 bar) of 2,3,4 trimet

Question

The normal boiling point (i.e boling point at 1 atm = 1.013 bar) of 2,3,4 trimethypentane, C8H18 is 113.47 and its molar enthalpy of vaporization is 37

600 kJ mol-1. What is the vapour pressure at 105.5C.

a) 0.6394 bar

b) 0.7819 bar

c) 0.7919 bar

d) 0.8213 bar

e) 0.9256 bar

2) Americium-241 is used in some smoke detectors. It undergoes nuclear decay via alpha emission, which is a first order proess with a half life of 432 years. How long will it take for 99.22% of the sample to decay?

a) 400 years

b) 654 years

c) 1512 years

d) 3024 years

e) 6048 years

THANKYOU IN ADVANCE, I WILL RAISE POINTS IF YOU FEEL IT IS NECASSARY!!

Explanation / Answer

2) t1/2 = 432

Time taken to decompose to 99.2% will be

ln(A0/0.00078A0) = kT(99.22)

T(99.22) = ln(1282)/ln(2) * 432 = 3023 years

Ans is 2(d)

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