This is a relatively easy half-life problem.
Whenever a half-life has expired, one half of the radioactive isotope will no longer be present.
When 2 half-lives have occurred, then one quarter of the isotope remains.
Therefore, the strontium - 90 will be at a safe level in 54 years.
<u>Answer:</u> The for the reaction is 15 kJ.
<u>Explanation:</u>
Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.
According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.
The given chemical reaction follows:
The intermediate balanced chemical reaction are:
(1) ( × 2)
(2)
(3)
The expression for enthalpy of the reaction follows:
Putting values in above equation, we get:
Hence, the for the reaction is 15 kJ.
Answer:
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