24.2: Mass Defect & Half Lives
Chapter 24
Dr. Robert E. Belford
Question 1
Given the following masses:
^{4}
He = 4.0026 g/mol
^{9}
Be = 9.0778 g/mol
^{12}
C = 12.0000g/mol
^{1}
n = 1.00866g/mol.
Calculate the energy released for the following reaction:
He + Be --> C + n
(A)
-3.56 x 10
^{9}
J
(B)
-6.46 x 10
^{12}
J
(C)
-8.77 x 10
^{23}
J
(D)
6.24 x 10
^{13}
J
Hint
Your response
Not answered yet
Question 2
How many grams of
^{222}
Rn are left after 7.0 days if a sample originally had 100.0 g and the half life is 3.82 days?
(A)
67.3 g
(B)
0.10g
(C)
28.1 g
(D)
9.89 g
Hint
Your response
Not answered yet
Question 3
How many grams of
^{226}
Ra are left after 7.0 days if a sample originally had 100.0 g and the half life is 8.0x10
^{4}
years?
(A)
0.124 g
(B)
100.0 g
(C)
45.0 g
(D)
1.070x10
^{-12 g }
Hint
Your response
Not answered yet
Question 4
How many grams of
^{214}
Po are left after 7.0 days if a sample originally had 100.0 g and the half life is 1.6
^{-4}
seconds?
(A)
0.00
(B)
38.4 g
(C)
100.0 g
(D)
0.125 g
Hint
Your response
Not answered yet