Answer:
The correct answer is B. It is spontaneous only at low temperatures.
Explanation:
In thermodynamics, the Gibbs free energy is a thermodynamic potential that can be used to calculate the maximum of reversible work that may be performed by a thermodynamic system at a constant temperature and pressure.
The spontaneity of a reaction is given by the equation:
ΔG = ΔH - TΔS
where:
ΔH: enthalpy variation
T: absolute temperature
ΔS: entropy variation
As the reaction is exothermic, ΔH<0
As the reaction order increases (the reagents are solid and gas and their product is solid), ΔS<0
Therefore, the reaction will be spontaneous when ΔG is negative.
ΔG = ΔH - TΔS
That is, the entropy term must be smaller than the enthalpy term.
Hence, the reaction will be spontaneous only at low temperatures.
Answer:
223.5 g
Explanation:
The formula between the number of moles, mass and Mr can be used to convert moles to grams.
<em>Number of moles = mass ÷ Mr</em>
So, mass = number of moles × Mr
Mr of Li₂O = (6.9 × 2) + 16 = 29.8
∴ Mass = 7.5 × 29.8 = <u>223.5 g</u>
