Answer:
-3.7771 × 10² kJ/mol
Explanation:
Let's consider the following equation.
3 Mg(s) + 2 Al³⁺(aq) ⇌ 3 Mg²⁺(aq) + 2 Al(s)
We can calculate the standard Gibbs free energy (ΔG°) using the following expression.
ΔG° = ∑np . ΔG°f(p) - ∑nr . ΔG°f(r)
where,
n: moles
ΔG°f(): standard Gibbs free energy of formation
p: products
r: reactants
ΔG° = 3 mol × ΔG°f(Mg²⁺(aq)) + 2 mol × ΔG°f(Al(s)) - 3 mol × ΔG°f(Mg(s)) - 2 mol × ΔG°f(Al³⁺(aq))
ΔG° = 3 mol × (-456.35 kJ/mol) + 2 mol × 0 kJ/mol - 3 mol × 0 kJ/mol - 2 mol × (-495.67 kJ/mol)
ΔG° = -377.71 kJ = -3.7771 × 10² kJ
This is the standard Gibbs free energy per mole of reaction.
The time the chocolate bar could power the laptop in hours is 0.00233 hrs.
Since 200 Calories of chocolate bar were burned to power the 100 Watt laptop, we need to find the number of joules on energy in 200 calories of chocolate bar.
Knowing that 4.2 Joules = 1 Calorie, then
200 Calories = 200 × 1 calorie = 200 × 4.2 Joules = 840 Joules
Since the power required by the laptop is 100 W = 100 J/s and Power, P = energy/time
so, time = energy/power
So, the time for the laptop to use 840 J of energy from the chocolate bar at a rate or power of 100 W = 100 J/s is
time = 840 J ÷ 100 J/s = 8.4 s
So, the time in hours is 8.4 s ÷ 3600 s/1 h = 0.00233 hrs (since 1 hr = 3600 s)
So, the time the chocolate bar could power the laptop in hours is 0.00233 hrs.
Learn more about time to power here:
brainly.com/question/17732603
