True or false If an atom is charged positive, it contains more protons than electrons.
1 answer:
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A. The radioactive decay equation is N = N0
where T is the half-life (5730 years), N0 is the number of atoms at time t = 0 and N is the number at time t.
Rewriting this as:
(N/N0) =
Since N = (1/8) N0 and substituting known values:
1/8 =
Taking ln of both sides:
ln(1/8)= -ln(2)*t/5730
t = - 5730 * ln(1/8) / ln (2)
t = 17,190 years
The tree was cut down 17,190 years ago.
B. N0 = 1,500,000 carbon-14 atoms
Since N = (1/8) N0
N = 187,500 carbon atoms left
Explanation:
As per the Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
Hence, according to this law the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
..........(1)
..............(2)
The final reaction is as follows:
.............(3)
Therefore, adding (1) and (2) we get the final equation (3) and value of at 298 K will be as follows.
=
+
= -314 kJ + (-80) kJ
= -394 kJ
Thus, we can conclude that at 298 K for the given process is -394 kJ.