In: Chemistry
1. The free energy available from a 1.78V Fe(III) – Ag cell under standard conditions is:
a. -515 KJ
b. +515 KJ
c. +172 KJ
d. -172 KJ
2. What is the nuclear binding energy for a mole of lithium-7 (Li-7), whose mass is 7.01600? (mass of a proton = 1.00728 AMU; neutron = 1.00866)
a. 6.34 x 1017J
b. 6.34 x 1014J
c. 3.64 x 1012J
d. 3.44 x 1015J
3. Tc-99 is commonly used in nuclear medicine studies. It has a half-life of 6 hours. How long does it take for less than 1% of the original injected isotope to remain?
a. 24 hours
b. 30 hours
c. 36 hours
d. 42 hours
ANSWER
Question 1
where n = number of electrons transferred and F = Faraday's constant = 96485 J / mol.V
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Question 2
where c = speed light = 3.00x108 m/s and m = mass defect of nucleus in kg
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Question 3
where A = final amount of isotope
A0 = initial amount of isotope
t = time
t1/2 = half-life