Environmental contingency plan is important to lessen or even prevent casualties or damage to infrastructures when unexpected environmental disasters happen. This is a common management strategy to lessen the costs of the company in the future. More importantly, it is used for safety purposes.
To solve for the enthalpy of reaction, we apply the Hess's Law.
ΔHrxn = ∑(ν×Hf of products) - ∑(ν×Hf of reactants)
where
v is the stoichiometric coefficient determined from the balanced reaction
Hf is the standard heat of formation; these are empirical values:
*For CH₄: Hf = <span>−74.87 kJ/mol
*For O</span>₂: Hf = 0
*For CO₂: <span>-393.5 kJ/mol
*For H</span>₂O: <span>-241.82 kJ/mol
</span>ΔHrxn = [(2*-241.82 kJ/mol)+(1*-393.5 kJ/mol)] - [(1*−74.87 kJ/mol)+(2*0 kJ/mol)] =<em> -802.27 kJ/mol</em>
For this problem, we use the formula for radioactive decay which is expressed as follows:
An = Aoe^-kt
where An is the amount left after time t, Ao is the initial amount and k is a constant.
We calculate as follows:
An = Aoe^-kt
0.5 = e^-k(5730)
k = 1.21x10^-4
An = Aoe^-kt
An = 200e^-1.21x10^-4(17190)
An = 25
Therefore, about 175g is produced.
