Answer:
DE2
Explanation: for every one D+2 you need two E-1 because +2=-2
Explanation:
As the Earth rotates on its axis and revolves around the Sun, several different effects are produced. When the new moon comes between the Earth and the Sun along the ecliptic, a solar eclipse is produced. When the Earth comes between the full moon and the Sun along the ecliptic, a lunar eclipse occurs.
Answer:
XY₂Z₄
2.35 mol Z
Explanation:
A sample of the compound contains 0.221 mol X, 0.442 mol Y, and 0.884 mol Z. We can find the simplest formula (empirical formula) by <em>dividing all the numbers of moles by the smallest one</em>.
X: 0.221/0.221 = 1
Y: 0.442/0.221 = 2
Z: 0.884/0.221 = 4
The simplest formula is XY₂Z₄.
The molar ratio of X to Z is 1:4. The moles of Z in a sample that contained 0.588 moles of X is:
0.588 mol X × (4 mol Z/1 mol X) = 2.35 mol Z
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.
